Showing papers in "Journal of Sleep Research in 2016"

The two-process model of sleep regulation: a reappraisal

Abstract: In the last three decades the two-process model of sleep regulation has served as a major conceptual framework in sleep research. It has been applied widely in studies on fatigue and performance and to dissect individual differences in sleep regulation. The model posits that a homeostatic process (Process S) interacts with a process controlled by the circadian pacemaker (Process C), with time-courses derived from physiological and behavioural variables. The model simulates successfully the timing and intensity of sleep in diverse experimental protocols. Electrophysiological recordings from the suprachiasmatic nuclei (SCN) suggest that S and C interact continuously. Oscillators outside the SCN that are linked to energy metabolism are evident in SCN-lesioned arrhythmic animals subjected to restricted feeding or methamphetamine administration, as well as in human subjects during internal desynchronization. In intact animals these peripheral oscillators may dissociate from the central pacemaker rhythm. A sleep/fast and wake/feed phase segregate antagonistic anabolic and catabolic metabolic processes in peripheral tissues. A deficiency of Process S was proposed to account for both depressive sleep disturbances and the antidepressant effect of sleep deprivation. The model supported the development of novel non-pharmacological treatment paradigms in psychiatry, based on manipulating circadian phase, sleep and light exposure. In conclusion, the model remains conceptually useful for promoting the integration of sleep and circadian rhythm research. Sleep appears to have not only a short-term, use-dependent function; it also serves to enforce rest and fasting, thereby supporting the optimization of metabolic processes at the appropriate phase of the 24-h cycle.

Sleep problems and internet addiction among children and adolescents: a longitudinal study

Abstract: Although the literature has documented associations between sleep problems and internet addiction, the temporal direction of these relationships has not been established. The purpose of this study is to evaluate the bidirectional relationships between sleep problems and internet addiction among children and adolescents longitudinally. A four-wave longitudinal study was conducted with 1253 children and adolescents in grades 3, 5 and 8 from March 2013 to January 2014. The sleep problems of the student participants were measured by parental reports on the Sleep Habit Questionnaire, which catalogues early insomnia, middle insomnia, disturbed circadian rhythm, periodic leg movements, sleep terrors, sleepwalking, sleep talking, nightmares, bruxism, snoring and sleep apnoea. The severity of internet addiction was measured by students' self-reports on the Chen Internet Addiction Scale. Based on the results of time-lag models, dyssomnias (odds ratio = 1.31), especially early and middle insomnias (odds ratio = 1.74 and 2.24), sequentially predicted internet addiction, and internet addiction sequentially predicted disturbed circadian rhythm (odds ratio = 2.40), regardless of adjustment for gender and age. This is the first study to demonstrate the temporal relationship of early and middle insomnia predicting internet addiction, which subsequently predicts disturbed circadian rhythm. These findings imply that treatment strategies for sleep problems and internet addiction should vary according to the order of their occurrence.

Sleep and academic performance in later adolescence: results from a large population-based study

Abstract: The aim of the current study was to assess the association between sleep duration and sleep patterns and academic performance in 16-19 year-old adolescents using registry-based academic grades. A large population-based study from Norway conducted in 2012, the youth@hordaland-survey, surveyed 7798 adolescents aged 16-19 years (53.5% girls). The survey was linked with objective outcome data on school performance. Self-reported sleep measures provided information on sleep duration, sleep efficiency, sleep deficit and bedtime differences between weekday and weekend. School performance [grade point average (GPA)] was obtained from official administrative registries. Most sleep parameters were associated with increased risk for poor school performance. After adjusting for sociodemographic information, short sleep duration and sleep deficit were the sleep measures with the highest odds of poor GPA (lowest quartile). Weekday bedtime was associated significantly with GPA, with adolescents going to bed between 22:00 and 23:00 hours having the best GPA. Also, delayed sleep schedule during weekends was associated with poor academic performance. The associations were somewhat reduced after additional adjustment for non-attendance at school, but remained significant in the fully adjusted models. In conclusion, the demonstrated relationship between sleep problems and poor academic performance suggests that careful assessment of sleep is warranted when adolescents are underperforming at school. Future studies are needed on the association between impaired sleep in adolescence and later functioning in adulthood.

Comparison of a single-channel EEG sleep study to polysomnography.

Abstract: Summary An accurate home sleep study to assess electroencephalography (EEG)-based sleep stages and EEG power would be advantageous for both clinical and research purposes, such as for longitudinal studies measuring changes in sleep stages over time. The purpose of this study was to compare sleep scoring of a single-channel EEG recorded simultaneously on the forehead against attended polysomnography. Participants were recruited from both a clinical sleep centre and a longitudinal research study investigating cognitively normal ageing and Alzheimer's disease. Analysis for overall epoch-by-epoch agreement found strong and substantial agreement between the single-channel EEG compared to polysomnography (κ = 0.67). Slow wave activity in the frontal regions was also similar when comparing the single-channel EEG device to polysomnography. As expected, Stage N1 showed poor agreement (sensitivity 0.2) due to lack of occipital electrodes. Other sleep parameters, such as sleep latency and rapid eye movement (REM) onset latency, had decreased agreement. Participants with disrupted sleep consolidation, such as from obstructive sleep apnea, also had poor agreement. We suspect that disagreement in sleep parameters between the single-channel EEG and polysomnography is due partially to altered waveform morphology and/or poorer signal quality in the single-channel derivation. Our results show that single-channel EEG provides comparable results to polysomnography in assessing REM, combined Stages N2 and N3 sleep and several other parameters, including frontal slow wave activity. The data establish that single-channel EEG can be a useful research tool.

Impact of continuous positive airway pressure (CPAP) on quality of life in patients with obstructive sleep apnea (OSA)

Abstract: Obstructive sleep apnea is a chronic illness with increasing prevalence. In addition to associated cardiovascular comorbidities, obstructive sleep apnea syndrome has been linked to poor quality of life, occupational accidents, and motor vehicle crashes secondary to excessive daytime sleepiness. Although continuous positive airway pressure is the gold standard for sleep apnea treatment, its effects on quality of life are not well defined. In the current study we investigated the effects of treatment on quality of life using the data from the Apnea Positive Pressure Long-term Efficacy Study (APPLES), a randomized controlled trial of continuous positive airway pressure (CPAP) versus sham CPAP. The Calgary Sleep Apnea Quality of Life Index (SAQLI) was used to assess quality of life. Overall we found no significant improvement in quality of life among sleep apnea patients after CPAP treatment. However, after stratifying by OSA severity, it was found that long-term improvement in quality of life might occur with the use of CPAP in people with severe and possibly moderate sleep apnea, and no demonstrable improvement in quality of life was noted among participants with mild obstructive sleep apnea.

Sleep duration estimates of Canadian children and adolescents

Abstract: The objective of this study was to provide contemporary sleep duration estimates of Canadian school-aged children and adolescents and to determine the proportion adhering to the sleep duration recommendations. This study included 24 896 participants aged 10-17 years from the 2013/2014 Canadian Health Behaviour in School-aged Children study (HBSC), a nationally representative cross-sectional study. Bedtime and wake-up times were reported by participants and their sleep duration was calculated. Participants were then classified as having a sleep duration that met the recommended range (9-11 h per night for 10-13-year-olds or 8-10 h per night for 14-17-year-olds), a sleep duration that was shorter than the recommended range or a sleep duration that was longer than the recommended range. An estimated 68% of children aged 10-13 years and 72% of adolescents aged 14-17 years sleep for the recommended amount per night when averaged across all days of the week. Short sleepers represent 31% of school-aged children and 26% of adolescents. Long sleepers are rare (<2% overall). Children and adolescents sleep ~1 h more at weekends compared to weekdays. Approximately 5% of the participants typically went to bed after midnight on weekdays and 31% did so at weekends; these proportions reached 11 and 45%, respectively, within 16-17-year-olds. In general, differences in sleep times between boys and girls are small and not clinically significant. In conclusion, almost one-third of Canadian children and adolescents sleep less than the recommended amount. Public health efforts should continue to monitor the sleep of Canadian children and adolescents and identify subgroups of the population more likely to be affected by insufficient sleep.

Phenotypes of comorbidity in OSAS patients: combining categorical principal component analysis with cluster analysis.

Abstract: Phenotyping obstructive sleep apnea syndrome's comorbidity has been attempted for the first time only recently. The aim of our study was to determine phenotypes of comorbidity in obstructive sleep apnea syndrome patients employing a data-driven approach. Data from 1472 consecutive patient records were recovered from our hospital's database. Categorical principal component analysis and two-step clustering were employed to detect distinct clusters in the data. Univariate comparisons between clusters included one-way analysis of variance with Bonferroni correction and chi-square tests. Predictors of pairwise cluster membership were determined via a binary logistic regression model. The analyses revealed six distinct clusters: A, 'healthy, reporting sleeping related symptoms'; B, 'mild obstructive sleep apnea syndrome without significant comorbidities'; C1: 'moderate obstructive sleep apnea syndrome, obesity, without significant comorbidities'; C2: 'moderate obstructive sleep apnea syndrome with severe comorbidity, obesity and the exclusive inclusion of stroke'; D1: 'severe obstructive sleep apnea syndrome and obesity without comorbidity and a 33.8% prevalence of hypertension'; and D2: 'severe obstructive sleep apnea syndrome with severe comorbidities, along with the highest Epworth Sleepiness Scale score and highest body mass index'. Clusters differed significantly in apnea-hypopnea index, oxygen desaturation index; arousal index; age, body mass index, minimum oxygen saturation and daytime oxygen saturation (one-way analysis of variance P < 0.0001). Binary logistic regression indicated that older age, greater body mass index, lower daytime oxygen saturation and hypertension were associated independently with an increased risk of belonging in a comorbid cluster. Six distinct phenotypes of obstructive sleep apnea syndrome and its comorbidities were identified. Mapping the heterogeneity of the obstructive sleep apnea syndrome may help the early identification of at-risk groups. Finally, determining predictors of comorbidity for the moderate and severe strata of these phenotypes implies a need to take these factors into account when considering obstructive sleep apnea syndrome treatment options.

Development of infant and toddler sleep patterns: real-world data from a mobile application.

Abstract: The aim of this study was to investigate the development of infant and toddler sleep patterns. Data were collected on 841 children (aged from birth to 36 months) via a free, publicly available, commercially sponsored iPhone app. Analyses were conducted on caregiver recordings of 156 989 sleep sessions across a 19-month period. Detailed visualizations of the development of sleep across the first 3 years of life are presented. In the first 3 months, sleep sessions primarily lasted less than 3.5 h throughout the day. Between 3 and 7 months old, sleep consolidated into two naps of about 1.5 h in length and a night-time sleep session of about 10.5 h. Across age groups, a negative relationship was observed between the start of bedtime and the length of the night-time sleep session (i.e. later bedtime is associated with a shorter night-time sleep period). The length of daytime sleep sessions (naps) varied with age, decreasing between 1 and 5 months old, and then increasing monotonically through 28 months. Morning wake time was observed to be invariant in children aged 5-36 months. Sleep patterns are ever-changing across the first few years with wide individual variability. Sleep patterns start to develop more clearly at 5-6 months, when longer night-time sleep duration begins and sleep consolidation occurs. Daytime sleep patterns appeared to become more consistent and consolidated later in age than night-time sleep. Finally, there is greater variability in bedtimes than wake times, with bedtimes having a greater influence on night-time sleep duration.

Prevalence of insomnia-related symptoms continues to increase in the Finnish working-age population.

Abstract: In 2008, we published epidemiological data from 1972 to 2005 that suggested an increase in insomnia-related symptoms among the working-age population. The results were based on the National FINRISK (FR) Study samples of the Finnish adult population aged 25-64, and on the Finnish Quality of Work Life Surveys (FQWLS), carried out among Finnish salary earners. Both of these ongoing studies have since provided two new estimates of insomnia-related symptoms. Chronic insomnia-related symptoms were 9.0% (95% CI 8.3-9.7), 9.6% (95% CI 8.8-10.4) in FR 2007 and 2012, respectively; and 9.1% (95% CI 8.3-10.0), 9.2% (95% CI 8.4-10.1) in FQWLS 2008 and 2013, respectively. Occasional insomnia-related symptoms were 45.3% (95% CI 44.1-46.6), 42.5% (95% CI 41.1-43.9) in FR 2007 and 2012, respectively; and 40.3% (95% CI 38.8-41.7), 44.8% (95% CI 41.1-43.9) in FQWLS 2008 and 2013, respectively. The new estimates further strengthen the interpretation of the ongoing increase in occasional insomnia-related symptoms among the Finnish general adult population. The increase in occasional symptoms was most prominent among employees. However, chronic insomnia symptoms showed no further increase.

Genome-wide association analysis of actigraphic sleep phenotypes in the LIFE Adult Study.

Abstract: The genetic basis of sleep is still poorly understood. Despite the moderate to high heritability of sleep-related phenotypes, known genetic variants explain only a small proportion of the phenotypical variance. However, most previous studies were based solely upon self-report measures. The present study aimed to conduct the first genome-wide association (GWA) of actigraphic sleep phenotypes. The analyses included 956 middle- to older-aged subjects (40-79 years) from the LIFE Adult Study. The SenseWear Pro 3 Armband was used to collect 11 actigraphic parameters of night- and daytime sleep and three parameters of rest (lying down). The parameters comprised measures of sleep timing, quantity and quality. A total of 7 141 204 single nucleotide polymorphisms (SNPs) were analysed after imputation and quality control. We identified several variants below the significance threshold of P ≤ 5× 10-8 (not corrected for analysis of multiple traits). The most significant was a hit near UFL1 associated with sleep efficiency on weekdays (P = 1.39 × 10-8 ). Further SNPs were close to significance, including an association between sleep latency and a variant in CSNK2A1 (P = 8.20 × 10-8 ), a gene known to be involved in the regulation of circadian rhythm. In summary, our GWAS identified novel candidate genes with biological plausibility being promising candidates for replication and further follow-up studies.

Higher sleep variability is associated with poorer glycaemic control in patients with type 1 diabetes.

Abstract: Summary Sleep disturbances have been linked to insulin resistance and poor glycaemic control in patients with type 2 diabetes. However, the data are limited in type 1 diabetes. Recently, varying day-to-day sleep schedules, i.e. sleep variability, have been associated with adverse metabolic profile in healthy individuals. This study explored whether sleep variability affects glycaemic control and insulin requirement in type 1 diabetes. Forty-one adult patients with type 1 diabetes wore an actigraphy for 5 nights. Standard deviation of sleep duration, efficiency and mid-sleep time were sleep variability parameters. Sleep apnoea risk and self-reported sleep quality were assessed by the Berlin questionnaire and Pittsburgh Sleep Quality Index. Haemoglobin A1c, diabetes complications and insulin regimen were obtained from medical records. After adjusting for neuropathic symptoms, sleep apnoea risk and poor self-reported sleep quality, higher sleep variability was significantly associated with poorer glycaemic control (standard deviation of sleep duration, B = 0.100, P = 0.004; and standard deviation of mid-sleep time, B = 0.068, P = 0.04). In addition, standard deviations of sleep duration and mid-sleep time were highly correlated, suggesting that participants changed their sleep duration along with sleep timing. After adjusting for covariates, the standard deviation of sleep duration (P = 0.009) and standard deviation of mid-sleep time (P = 0.012) were associated with higher insulin requirement. In summary, higher sleep variability, which likely reflects sleep deprivation alternating with sleep compensation along with shifts in their circadian timing, was associated with poorer glycaemic control and higher insulin requirement in patients with type 1 diabetes. Increased sleep regularity may improve metabolic control in type 1 diabetes.

Characterization of obstructive sleep apnea-hypopnea syndrome (OSA) population by means of cluster analysis.

Abstract: Obstructive sleep apnea-hypopnea syndrome (OSA) is being identified increasingly as an important health issue It is typified by repeated episodes of upper airway collapse during sleep leading to occasional hypoxaemia, sleep fragmentation and poor sleep quality OSA is also being considered as an independent risk factor for hypertension, diabetes and cardiovascular diseases, leading to increased multi-morbidity and mortality Cluster analysis, a powerful statistical set of techniques, may help in investigating and classifying homogeneous groups of patients with similar OSA characteristics This study aims to investigate the (possible) different groups of patients in an OSA population, and to analyse the relationships among the main clinical variables in each group to better understand the impact of OSA on patients Starting from a well-characterized OSA population of 198 subjects afferent to our sleep centre, we identified three different communities of OSA patients The first has a very severe disease [apnea-hypopnea index (AHI) = 6591 ± 2247] and sleep disorder has a strong impact on daily life: a low level of diurnal partial pressure of oxygen (PaO2 ) (7739 ± 1164 mmHg) and a high prevalence of hypertension (64%); the second, with less severe disease (AHI = 2888 ± 1713), in which sleep disorders seem to be less important for diurnal PaO2 and have a minimum impact on comorbidity; and the last with very severe OSA (AHI = 5726 ± 1509) but with a low risk of nocturnal hypoxaemia (T90 = 1158 ± 854) and less sleepy (Epworth Sleepiness Scale 1000 ± 477)

Chronic kidney disease in European patients with obstructive sleep apnea: the ESADA cohort study.

Abstract: Summary The cross-sectional relationship of obstructive sleep apnea with moderate to severe chronic kidney disease, defined as an estimated glomerular filtration rate <60 mL min−1∙173 m−2, was investigated in a large cohort of patients with suspected obstructive sleep apnea studied by nocturnal polysomnography or cardiorespiratory polygraphy Data were obtained from the European Sleep Apnea Database, where information from unselected adult patients with suspected obstructive sleep apnea afferent to 26 European sleep centres had been prospectively collected Both the Modification of Diet in Renal Disease and the Chronic Kidney Disease-Epidemiology Collaboration equations were used for the assessment of estimated glomerular filtration rate The analysed sample included 7700 subjects, 71% male, aged 519 ± 125 years Severe obstructive sleep apnea (apnea–hypopnea index ≥30) was found in 34% of subjects The lowest nocturnal oxygen saturation was 81 ± 102% Chronic kidney disease prevalence in the whole sample was 87% or 61%, according to the Modification of Diet in Renal Disease or the Chronic Kidney Disease-Epidemiology Collaboration equations, respectively Subjects with lower estimated glomerular filtration rate were older, more obese, more often female, had worse obstructive sleep apnea and more co-morbidities (P < 0001, each) With both equations, independent predictors of estimated glomerular filtration rate <60 were: chronic heart failure; female gender; systemic hypertension; older age; higher body mass index; and worse lowest nocturnal oxygen saturation It was concluded that in obstructive sleep apnea, chronic kidney disease is largely predicted by co-morbidities and anthropometric characteristics In addition, severe nocturnal hypoxaemia, even for only a small part of the night, may play an important role as a risk factor for kidney dysfunction

A single night of partial sleep loss impairs fasting insulin sensitivity but does not affect cephalic phase insulin release in young men.

Abstract: The present study sought to investigate whether a single night of partial sleep deprivation (PSD) would alter fasting insulin sensitivity and cephalic phase insulin release (CPIR) in humans. A rise in circulating insulin in response to food-related sensory stimulation may prepare tissues to break down ingested glucose, e.g. by stimulating rate-limiting glycolytic enzymes. In addition, given insulin's anorexigenic properties once it reaches the brain, the CPIR may serve as an early peripheral satiety signal. Against this background, in the present study 16 men participated in two separate sessions: one night of PSD (4.25 h sleep) versus one night of full sleep (8.5 h sleep). In the morning following each sleep condition, subjects' oral cavities were rinsed with a 1-molar sucrose solution for 45 s, preceded and followed by blood sampling for repeated determination of plasma glucose and serum insulin concentrations (-3, +3, +5, +7, +10 and +20 min). Our main result was that PSD, compared with full sleep, was associated with significantly higher peripheral insulin resistance, as indicated by a higher fasting homeostasis model assessment of insulin resistance index (+16%, P = 0.025). In contrast, no CPIR was observed in any of the two sleep conditions. Our findings indicate that a single night of PSD is already sufficient to impair fasting insulin sensitivity in healthy men. In contrast, brief oral cavity rinsing with sucrose solution did not change serum insulin concentrations, suggesting that a blunted CPIR is an unlikely mechanism through which acute sleep loss causes metabolic perturbations during morning hours in humans.

Association of incident restless legs syndrome with outcomes in a large cohort of US veterans

Abstract: Restless legs syndrome is a common sleep disorder, but there is a paucity of large cohort studies examining the association of restless legs syndrome with clinical outcomes, including all-cause mortality, incident coronary heart disease, stroke and chronic kidney disease. From a nationally representative prospective cohort of over 3 million US veterans [93% male, median follow-up time of 8.1 years (interquartile range: 7.0-8.5 years)] with baseline estimated glomerular filtration rate ≥ 60 mL min(-1) 1.73 m(-2), a propensity-matched cohort of 7392 patients was created, and the association between incident restless legs syndrome and the following was examined: (1) all-cause mortality; (2) incident coronary heart disease; (3) incident strokes; and (4) incident chronic kidney disease defined as estimated glomerular filtration rate <60 mL min(-1) 1.73 m(-2). Associations were examined using Cox models. The mean ± SD age of the propensity-matched cohort at baseline was 59 ± 12 years; 89 and 8% of patients were white and black, respectively; 31% of the patients were diabetic; and the mean baseline estimated glomerular filtration rate was 83.9 ± 15.1 mL min(-1) 1.73 m(-2). Propensity matching resulted in a balanced cohort, with the disappearance in baseline differences in comorbidities. Compared with restless legs syndrome-negative patients, incident restless legs syndrome was associated with 88% higher mortality risk [hazard ratio and 95% confidence interval: 1.88 (1.70-2.08)], and almost four times higher risk of coronary heart disease and stroke [hazard ratio: 3.97 (3.26-4.84) and 3.89 (3.07-4.94), respectively]. The risk of incident chronic kidney disease was also significantly higher in incident restless legs syndrome patients [hazard ratio: 3.17 (2.74-3.66)] compared with restless legs syndrome-negative counterparts. In this large and contemporary cohort of US veterans, incident restless legs syndrome was associated with higher risk of mortality, incident coronary heart disease, stroke and chronic kidney disease.

How to measure snoring? A comparison of the microphone, cannula and piezoelectric sensor.

Abstract: The objective of this study was to compare to each other the methods currently recommended by the American Academy of Sleep Medicine (AASM) to measure snoring: an acoustic sensor, a piezoelectric sensor and a nasal pressure transducer (cannula) Ten subjects reporting habitual snoring were included in the study, performed at Landspitali-University Hospital, Iceland Snoring was assessed by listening to the air medium microphone located on a patient's chest, compared to listening to two overhead air medium microphones (stereo) and manual scoring of a piezoelectric sensor and nasal cannula vibrations The chest audio picked up the highest number of snore events of the different snore sensors The sensitivity and positive predictive value of scoring snore events from the different sensors was compared to the chest audio: overhead audio (078, 098), cannula (055, 067) and piezoelectric sensor (078, 092), respectively The chest audio was capable of detecting snore events with lower volume and higher fundamental frequency than the other sensors The 200 Hz sampling rate of the cannula and piezoelectric sensor was one of their limitations for detecting snore events The different snore sensors do not measure snore events in the same manner This lack of consistency will affect future research on the clinical significance of snoring Standardization of objective snore measurements is therefore needed Based on this paper, snore measurements should be audio-based and the use of the cannula as a snore sensor be discontinued, but the piezoelectric sensor could possibly be modified for improvement

Gender differences in patients with obesity hypoventilation syndrome

Abstract: The role of gender and menopause in obstructive sleep apnoea is well known; however, no study has reported the impact of gender on the clinical presentation and the nocturnal respiratory events in patients with obesity hypoventilation syndrome. Therefore, this study prospectively evaluated differences in the clinical characteristics of women and men with obesity hypoventilation syndrome in a large cohort of patients with obstructive sleep apnoea. During the study period, a total of 1973 patients were referred to the sleep clinic with clinical suspicion of obstructive sleep apnoea. All patients underwent overnight polysomnography, during which time spirometry, arterial blood samples and thyroid tests were routinely obtained. Among 1973 consecutive patients, 1693 (617 women) were diagnosed with obstructive sleep apnoea, among whom 144 suffered from obesity hypoventilation syndrome (96 women). The prevalence of obesity hypoventilation syndrome among women and men was 15.6% and 4.5%, respectively (P < 0.001). Women with obesity hypoventilation syndrome were significantly older than men with obesity hypoventilation syndrome (61.5 ± 11.9 years versus 49.1 ± 12.5 years, P < 0.001). Although there were no significant differences between genders regarding symptoms, body mass index, spirometric data or daytime PaCO2 , women with obesity hypoventilation syndrome suffered significantly more from hypertension, diabetes and hypothyroidism. The prevalence of obesity hypoventilation syndrome was higher in post-menopausal (21%) compared with pre-menopausal (5.3%) women (P < 0001). HCO3 and duration of SpO2 <90% were the only independent predictors of obesity hypoventilation syndrome. In conclusion, this study reported that among subjects referred to the sleep disorders clinic for evaluation of obstructive sleep apnoea, obesity hypoventilation syndrome is more prevalent in women than men, and that women with obesity hypoventilation syndrome suffer from significantly more co-morbidities. Post-menopausal women with obstructive sleep apnoea have the highest prevalence of obesity hypoventilation syndrome.

Assessment of the suitability of using a forehead EEG electrode set and chin EMG electrodes for sleep staging in polysomnography.

Abstract: Recently, a number of portable devices designed for full polysomnography at home have appeared. However, current scalp electrodes used for electroencephalograms are not practical for patient self-application. The aim of this study was to evaluate the suitability of recently introduced forehead electroencephalogram electrode set and supplementary chin electromyogram electrodes for sleep staging. From 31 subjects (10 male, 21 female; age 31.3 ± 11.8 years), sleep was recorded simultaneously with a forehead electroencephalogram electrode set and with a standard polysomnography setup consisting of six recommended electroencephalogram channels, two electrooculogram channels and chin electromyogram. Thereafter, two experienced specialists scored each recording twice, based on either standard polysomnography or forehead recordings. Sleep variables recorded with the forehead electroencephalogram electrode set and separate chin electromyogram electrodes were highly consistent with those obtained with the standard polysomnography. There were no statistically significant differences in total sleep time, sleep efficiency or sleep latencies. However, compared with the standard polysomnography, there was a significant increase in the amount of stage N1 and N2, and a significant reduction in stage N3 and rapid eye movement sleep. Overall, epoch-by-epoch agreement between the methods was 79.5%. Inter-scorer agreement for the forehead electroencephalogram was only slightly lower than that for standard polysomnography (76.1% versus 83.2%). Forehead electroencephalogram electrode set as supplemented with chin electromyogram electrodes may serve as a reliable and simple solution for recording total sleep time, and may be adequate for measuring sleep architecture. Because this electrode concept is well suited for patient's self-application, it may offer a significant advancement in home polysomnography.

The European Narcolepsy Network (EU-NN) database.

Abstract: Narcolepsy with cataplexy is a rare disease with an estimated prevalence of 0.02% in European populations. Narcolepsy shares many features of rare disorders, in particular the lack of awareness of the disease with serious consequences for healthcare supply. Similar to other rare diseases, only a few European countries have registered narcolepsy cases in databases of the International Classification of Diseases or in registries of the European health authorities. A promising approach to identify disease-specific adverse health effects and needs in healthcare delivery in the field of rare diseases is to establish a distributed expert network. A first and important step is to create a database that allows collection, storage and dissemination of data on narcolepsy in a comprehensive and systematic way. Here, the first prospective web-based European narcolepsy database hosted by the European Narcolepsy Network is introduced. The database structure, standardization of data acquisition and quality control procedures are described, and an overview provided of the first 1079 patients from 18 European specialized centres. Due to its standardization this continuously increasing data pool is most promising to provide a better insight into many unsolved aspects of narcolepsy and related disorders, including clear phenotype characterization of subtypes of narcolepsy, more precise epidemiological data and knowledge on the natural history of narcolepsy, expectations about treatment effects, identification of post-marketing medication side-effects, and will contribute to improve clinical trial designs and provide facilities to further develop phase III trials.

Human amygdala activation during rapid eye movements of rapid eye movement sleep: an intracranial study.

Abstract: The amygdaloid complex plays a crucial role in processing emotional signals and in the formation of emotional memories. Neuroimaging studies have shown human amygdala activation during rapid eye movement sleep (REM). Stereotactically implanted electrodes for presurgical evaluation in epileptic patients provide a unique opportunity to directly record amygdala activity. The present study analysed amygdala activity associated with REM sleep eye movements on the millisecond scale. We propose that phasic activation associated with rapid eye movements may provide the amygdala with endogenous excitation during REM sleep. Standard polysomnography and stereo-electroencephalograph (SEEG) were recorded simultaneously during spontaneous sleep in the left amygdala of four patients. Time-frequency analysis and absolute power of gamma activity were obtained for 250 ms time windows preceding and following eye movement onset in REM sleep, and in spontaneous waking eye movements in the dark. Absolute power of the 44-48 Hz band increased significantly during the 250 ms time window after REM sleep rapid eye movements onset, but not during waking eye movements. Transient activation of the amygdala provides physiological support for the proposed participation of the amygdala in emotional expression, in the emotional content of dreams and for the reactivation and consolidation of emotional memories during REM sleep, as well as for next-day emotional regulation, and its possible role in the bidirectional interaction between REM sleep and such sleep disorders as nightmares, anxiety and post-traumatic sleep disorder. These results provide unique, direct evidence of increased activation of the human amygdala time-locked to REM sleep rapid eye movements.

Objective but not subjective sleep predicts memory in community-dwelling older adults

Abstract: Research on the relationship between habitual sleep patterns and memory performance in older adults is limited. No previous study has used objective and subjective memory measures in a large, older-aged sample to examine the association between sleep and various domains of memory. The aim of this study was to examine the association between objective and subjective measures of sleep with memory performance in older adults, controlling for the effects of potential confounds. One-hundred and seventy-three community-dwelling older adults aged 65-89 years in Victoria, Australia completed the study. Objective sleep quality and length were ascertained using the Actiwatch 2 Mini-Mitter, while subjective sleep was measured using the Pittsburgh Sleep Quality Index. Memory was indexed by tests of retrospective memory (Hopkins Verbal Learning Test - Revised), working memory (n-back, 2-back accuracy) and prospective memory (a habitual button pressing task). Compared with normative data, overall performance on retrospective memory function was within the average range. Hierarchical regression was used to determine whether objective or subjective measures of sleep predicted memory performances after controlling for demographics, health and mood. After controlling for confounds, actigraphic sleep indices (greater wake after sleep onset, longer sleep-onset latency and longer total sleep time) predicted poorer retrospective (∆R(2) = 0.05, P = 0.016) and working memory (∆R(2) = 0.05, P = 0.047). In contrast, subjective sleep indices did not significantly predict memory performances. In community-based older adults, objectively-measured, habitual sleep indices predict poorer memory performances. It will be important to follow the sample longitudinally to determine trajectories of change over time.

Beta EEG reflects sensory processing in active wakefulness and homeostatic sleep drive in quiet wakefulness.

Abstract: Markers of sleep drive (<10 Hz; slow-wave activity and theta) have been identified in the course of slow-wave sleep and wakefulness. So far, higher frequencies in the waking electroencephalogram have not been examined thoroughly as a function of sleep drive. Here, electroencephalogram dynamics were measured in epochs of active wake (wake characterized by high muscle tone) or quiet wake (wake characterized by low muscle tone). It was hypothesized that the higher beta oscillations (15-35 Hz, measured by local field potential and electroencephalography) represent fundamentally different processes in active wake and quiet wake. In active wake, sensory stimulation elevated beta activity in parallel with gamma (80-90 Hz) activity, indicative of cognitive processing. In quiet wake, beta activity paralleled slow-wave activity (1-4 Hz) and theta (5-8 Hz) in tracking sleep need. Cerebral lactate concentration, a measure of cerebral glucose utilization, increased during active wake whereas it declined during quiet wake. Mathematical modelling of state-dependent dynamics of cortical lactate concentration was more precisely predictive when quiet wake and active wake were included as two distinct substates rather than a uniform state of wakefulness. The extent to which lactate concentration declined in quiet wake and increased in active wake was proportionate to the amount of beta activity. These data distinguish quiet wake from active wake. Quiet wake, particularly when characterized by beta activity, is permissive to metabolic and electrophysiological changes that occur in slow-wave sleep. These data urge further studies on state-dependent beta oscillations across species.

The prevalence and characteristics of obstructive sleep apnea in hospitalized patients with type 2 diabetes in China.

Abstract: Data on the prevalence of obstructive sleep apnea in subjects with type 2 diabetes mellitus in China is scarce. We conducted a multi-centre, cross-sectional study involving 12 hospitals from six regional cities to investigate the prevalence of obstructive sleep apnea in hospitalized patients with type 2 diabetes mellitus and to explore the association between obstructive sleep apnea and related risk factors, diabetic complications and comorbidities in China. Each hospital recruited at least 70 consecutive patients with type 2 diabetes mellitus who were admitted to the endocrinology ward. A total of 880 participants were enrolled and administered overnight sleep monitoring with a portable monitor (ApneaLink™, ResMed, San Diego, CA, USA); other information was collected from medical charts and a standardized questionnaire. In this study, 60.0% (95% confidence interval: 56.8%, 63.2%) of hospitalized patients in China with type 2 diabetes mellitus had comorbid obstructive sleep apnea (apnea-hypopnea index ≥ 5). Only 1.5% (eight of 528) of the patients with both conditions had been diagnosed previously with obstructive sleep apnea. The prevalence of moderate-severe (apnea-hypopnea index ≥ 15) and severe obstructive sleep apnea (apnea-hypopnea index ≥ 30) was estimated to be 25.6% (22.7, 28.5%) and 10.3% (8.3, 12.4%), respectively. Age, sex, body mass index, snoring, reported breath-holding in sleep or gasping or choking arousal, sleepiness, diabetes duration, hypertension, diabetic nephropathy and cardiovascular diseases history were correlated significantly with the severity of obstructive sleep apnea. In China, the prevalence of obstructive sleep apnea in hospitalized patients with type 2 diabetes mellitus is high. Routine screening for and treatment of obstructive sleep apnea is an important, but often neglected, part of the management of diabetes.

Diagnostic delay in narcolepsy type 1: combining the patients' and the doctors' perspectives.

Abstract: Narcolepsy type 1 is a neurological disorder characterized by a unique syndrome, including the pathognomonic symptom of cataplexy. The diagnosis can be confirmed by objective measures, such as typical findings in the multiple sleep latency test, reduced or undetectable levels of orexin (hypocretin) in the cerebrospinal fluid, and linkage to a specific HLA haplotype. Nevertheless, the mean time that elapses from symptom onset to the correct diagnosis ranges between 10 and 20 years, and the causes and correlates of this delay are poorly understood. Diagnostic delay was assessed on 52 well-defined patients with narcolepsy type 1, evaluating clinical, electrophysiological and neurochemical parameters and the results of a 41-item questionnaire developed to obtain the patients' perspective on various aspects of the diagnostic process. The mean time gap between disease onset and first medical consultation was 3.2 ± 5.1 years; the mean diagnostic delay was 8.9 ± 11.0 years. Prior to correct diagnosis, patients received a wide variety of misdiagnoses. The self-ratings of the patients revealed that the undiagnosed symptoms caused high levels of anxiety and unjustified criticism by family, friends and employers. Multiple regression analysis identified higher cerebrospinal fluid orexin levels (β = 0.311, P = 0.01), and a longer interval between the onset of excessive daytime sleepiness and cataplexy (β = 0.368, P = 0.002) as independent associates of longer diagnostic delay. The diagnostic delay decreased over the last decades (β = -0.672, P < 0.001). In conclusion, delayed diagnosis of narcolepsy type 1 is very common, associated with many adverse consequences, and requires educational efforts to improve awareness on narcolepsy among healthcare providers and the general population.

Sleep deprivation increases formation of false memory

Abstract: Summary Retrieving false information can have serious consequences. Sleep is important for memory, but voluntary sleep curtailment is becoming more rampant. Here, the misinformation paradigm was used to investigate false memory formation after 1 night of total sleep deprivation in healthy young adults (N = 58, mean age ± SD = 22.10 ± 1.60 years; 29 males), and 7 nights of partial sleep deprivation (5 h sleep opportunity) in these young adults and healthy adolescents (N = 54, mean age ± SD = 16.67 ± 1.03 years; 25 males). In both age groups, sleep-deprived individuals were more likely than well-rested persons to incorporate misleading post-event information into their responses during memory retrieval (P < 0.050). These findings reiterate the importance of adequate sleep in optimal cognitive functioning, reveal the vulnerability of adolescents' memory during sleep curtailment, and suggest the need to assess eyewitnesses' sleep history after encountering misleading information.

Circadian variation of metabotropic glutamate receptor 5 availability in the rat brain

Abstract: The metabotrophic subtype 5 glutamate receptor (mGluR5) plays a critical role in synaptic plasticity besides its involvement in numerous neurological disorders, such as depression. As mGluR5 availability in humans is altered in sleep deprivation, we hypothesized that mGluR5 availability underlies a circadian variation. To investigate whether mGluR5 underlies potential circadian changes we measured its density in a randomized fashion at six different daytimes in 11 adult Sprague-Dawley rats. mGluR5 density was quantified by positron emission tomography (PET) using the radioactive ligand [11 C]ABP688. [11 C]ABP688 uptake was quantified in nine regions of interest with a reference tissue model. Significant differences in the binding potential (BPND ) and therefore mGluR5 availability between the different circadian times were found in cortex, cingulate cortex, amygdala, caudate putamen and nucleus accumbens. Further post-hoc statistical analysis (Tukey-Kramer test) of the different time-points revealed significant changes in BPND between 07:00 hours (start of light-on phase) and 15:00 hours (last time-point of the light-on phase) in the caudate putamen. This study shows that mGluR5 availability is increased during the light-on, or sleep phase, of rodents by approximately 10%. Given that altered mGluR5 densities play a role in psychiatric disorders, further investigation is warranted to evaluate their circadian involvement in mood changes in humans.

Disturbed sleep in attention-deficit hyperactivity disorder (ADHD) is not a question of psychiatric comorbidity or ADHD presentation.

Abstract: Attention-deficit hyperactivity disorder (ADHD) is a heterogeneous psychiatric disorder with three different presentations and high levels of psychiatric comorbidity. Serious sleep complaints are also common, but the role of the presentations and comorbidity in sleep is under-investigated in ADHD. Consequently, the goal of the study was to investigate sleep problems in medicine-naive school-aged children (mean age = 9.6 years) with ADHD compared to controls using objective methods and to examine the role of comorbidity and presentations. Ambulatory polysomnography results suggested that children with ADHD (n = 76) had significantly more sleep disturbances than controls (n = 25), including a larger percentage of rapid eye movement (REM) sleep and more sleep cycles, as well as lower mean sleep efficiency, mean non-REM (NREM) sleep stage 1 and mean NREM sleep stage 3. No significant between-group differences were found on the multiple sleep latency test. Stratifying for comorbidity in the ADHD group did not reveal major differences between groups, but mean sleep latency was significantly longer in children with ADHD and no comorbidity compared to controls (36.1 min; SD = 30.1 versus 22.6 min; SD = 15.2). No differences were found between ADHD presentations. Our results support the presence of night-time sleep disturbances in children with ADHD. Poor sleep does not appear to be attributable to comorbidity alone, nor do sleep disturbances differ within ADHD presentations.

Winter is coming: nightmares and sleep problems during seasonal affective disorder

Abstract: Sleep problems, especially nightmares and insomnia, often accompany depression. This study investigated how nightmares, symptoms of insomnia, chronotype and sleep duration associate with seasonal affective disorder, a special form of depression. Additionally, it was noted how latitude, a proxy for photoperiod, and characteristics of the place of residence affect the prevalence of seasonal affective disorder and sleep problems. To study these questions, data from FINRISK 2012 study were used. FINRISK 2012 consists of a random population sample of Finnish adults aged 25-74 years (n = 4905) collected during winter from Finnish urban and rural areas spanning the latitudes of 60°N to 66°N. The Seasonal Pattern Assessment Questionnaire was used to assess symptoms of seasonal affective disorder. Participants with symptoms of seasonal affective disorder had significantly increased odds of experiencing frequent nightmares and symptoms of insomnia, and they were more often evening chronotypes. Associations between latitude, population size and urbanicity with seasonal affective disorder symptoms and sleep disturbances were generally not significant, although participants living in areas bordering urban centres had less sleep problems than participants from other regions. These data show that the prevalence of seasonal affective disorder was not affected by latitude.

Parenting matters: a longitudinal study into parenting and adolescent sleep

Abstract: Summary The current three-wave longitudinal study examined the differential relations between general parenting behaviour (monitoring, autonomy granting, and the quality of the parent–adolescent relationship) and adolescent sleep (bedtimes, time in bed, sleep quality and sleepiness) over a period of 2 years At Time 1, the sample consisted of 650 adolescents between 12 and 15 years old (M = 1336 years; SD = 055 years) At Time 2, 563 adolescents participated, and at Time 3 there were 493 adolescents The distribution of boys and girls was about equal Adolescents completed questionnaires in the classroom Linear mixed model analyses were performed, controlling for sex, age, social economic status and ethnicity Results showed that higher levels of monitoring contributed to earlier bedtimes, longer time in bed, better sleep quality and less sleepiness The parent–adolescent relationship quality showed positive associations with time in bed, sleep quality and sleepiness, but not with bedtimes Autonomy granting appeared hardly to be related to any of the sleep variables In addition, passing of time, sex and ethnicity contributed to adolescent sleep as main effects or in interaction with parental control and support, suggesting that the main effects of monitoring and the quality of the parent–adolescent relationship are not constant across the whole range of the covariates Based on the findings of this study, it can be concluded that general parenting behaviour may contribute to better adolescent sleep over time Therefore, the involvement of parents in improvement of adolescent sleep is highly advocated

Actigraphic sleep fragmentation, efficiency and duration associate with dietary intake in the Rotterdam Study

Abstract: Short self-reported sleep duration is associated with dietary intake and this association may partly mediate the link between short sleep and metabolic abnormalities. Subjective sleep measures, however, may be inaccurate and biased. The objective of this study was to evaluate the associations between actigraphic measures of sleep fragmentation, efficiency and duration and energy and macronutrient intakes. We used data from a subgroup of 439 participants of the population-based cohort, Rotterdam Study. Sleep was assessed using 7-day actigraphy and sleep diaries, and dietary data with a validated food frequency questionnaire. We assessed the associations of actigraphic sleep parameters with dietary intake using multivariable linear regression models. Higher sleep fragmentation was associated with 4.19 g lower carbohydrate intake per standard deviation of fragmentation {β [95% confidence interval (CI) = -4.19 (-8.0, -0.3)]; P = 0.03}. Each additional percentage increase in sleep efficiency was associated with 11.1 kcal lower energy intake [β (95% CI) = -11.1 (-20.6, -1.7); P = 0.02]. Furthermore, very short sleep duration (<5.5 h) was associated with 218.1 kcal higher energy intake [β (95% CI = 218.06 (33.3, 402.8), P = 0.02], relative to the reference group (≥6.5 to <7.5 h). We observed associations between higher sleep fragmentation with lower carbohydrate intake, and both lower sleep efficiency and very short sleep duration (<5 h) with higher energy intake. The association between sleep and higher energy intake could mediate, in part, the link between short sleep or sleep fragmentation index and metabolic abnormalities.