Showing papers in "Journal of Sleep Research in 2007"

Prevalence and correlates of clinical insomnia co-occurring with chronic back pain

Abstract: Given the suggestion of a reciprocal relationship between sleep and pain and the recognition of sleep as an important parameter in determining quality of life, there is increasing research interest in sleep disturbance linked to chronic pain. The present study aimed to provide an estimate of the prevalence of 'clinical insomnia' in patients attending a specialist pain clinic and identify factors associated with it. Seventy chronic back pain patients and 70 gender- and age-matched pain-free controls completed a set of questionnaires measuring sleep (Insomnia Severity Index; ISI), pain (Short-Form McGill Pain Questionnaire) and a selection of general and specific psychological variables (Hospital Anxiety and Depression Scale, Short Health Anxiety Inventory). Scores suggestive of clinical insomnia (ISI > or = 15) were noted in 53% of chronic pain patients, when compared with only 3% in pain-free controls. Significant positive correlations with insomnia severity were detected for all six variables of interest (pain intensity, sensory pain ratings, affective pain ratings, general anxiety, general depression and health anxiety). Affective pain ratings and health anxiety were the best predictors of insomnia severity in this sample, accounting for 30% of the total variance, even when present pain intensity was controlled for. Affective pain remained as a significant predictor of insomnia severity when both the effect of pain intensity and the effects of anxiety and depression were controlled for. Future research should consider investigating the role of pain appraisal and health anxiety in the development and manifestation of insomnia concomitant to chronic pain.

The association between sleep duration, body mass index and metabolic measures in the Hordaland Health Study

Abstract: Several studies show that short self-reported sleep duration is associated with elevated body mass index (BMI). Short sleep duration may change appetite hormones, but whether this also influences metabolic measures like cholesterol and triglycerides is less clear. Furthermore, obesity is linked to increases in blood pressure, and recently, short sleep duration has been shown to be an independent risk factor for hypertension. This is a population-based cross-sectional study (The Hordaland Health Study). A subgroup of 8860 subjects, aged 40-45 years, answered a sleep questionnaire. Body weight, height and blood pressure were measured, and non-fasting blood samples were collected and analyzed for total cholesterol, HDL-cholesterol and triglycerides. Sleep duration was divided into the following subgroups: or = 9 h. The results show that short sleep duration was associated with elevated BMI and increased prevalence of obesity. Similar to BMI, levels of cholesterol, triglycerides, systolic and diastolic blood pressure were higher in subjects with short sleep duration. This co-variation seemed to be attributed to variables like gender, smoking and BMI. In conclusion, our study confirms a clear association between short sleep duration and elevated BMI and obesity. Furthermore, levels of total cholesterol, HDL-cholesterol, triglycerides and blood pressure were associated with sleep duration.

Sleep habits and circadian preference in Italian children and adolescents

Abstract: Sleep habits and circadian preference (morningness/eveningness, M/E) have been extensively analyzed in adolescents and young adults, while few studies were conducted on children and early adolescents. Aim of the present study was to investigate the developmental changes of circadian preference and to analyze its relationship with sleep habits, sleep problems and circadian preference in a large sample by means of a school-based survey. One thousand seventy-three participants (50.8% boys and 49.2% girls; mean age = 10.6; range = 8-14 years), recruited from four schools randomly extracted within the district of Rome, completed a modified version of School Sleep Habits Survey developed by Carskadon et al. The questionnaire included items about sleep habits during schooldays and weekends; a Sleepiness Scale; a Sleep-Wake Problems Behaviour Scale; a Morningness/Eveningness scale. The results show a consistent age-related change in sleep habits, particularly in the weekends. The difference in sleep duration between schooldays and weekends increases linearly with age. No gender difference was observed in morningness/eveningness, while a significant linear increase in evening preference was found with increasing ages. M/E total scores correlated significantly with both self-reported sleep/wake problems and daytime sleepiness indicating a higher prevalence of sleep complaints in evening-type subjects. Overall, the present results support the existence of consistent age-related changes in sleep habits and M/E dimension in the 8- to 14-year age range.

Prolonged‐release melatonin improves sleep quality and morning alertness in insomnia patients aged 55 years and older and has no withdrawal effects

Abstract: Melatonin, secreted nocturnally by the pineal gland, is an endogenous sleep regulator. Impaired melatonin production and complaints on poor quality of sleep are common among the elderly. Non-restorative sleep (perceived poor quality of sleep) and subsequently poor daytime functioning are increasingly recognized as a leading syndrome in the diagnostic and therapeutic process of insomnia complaints. The effects of 3-weeks prolonged-release melatonin 2 mg (PR-melatonin) versus placebo treatment were assessed in a multi-center randomized placebo-controlled study in 170 primary insomnia outpatients aged > or =55 years. Improvements in quality of sleep (QOS) the night before and morning alertness (BFW) were assessed using the Leeds Sleep Evaluation Questionnaire and changes in sleep quality (QON) reported on five categorical unit scales. Rebound insomnia and withdrawal effects following discontinuation were also evaluated. PR-melatonin significantly improved QOS (-22.5 versus -16.5 mm, P = 0.047), QON (0.89 versus 0.46 units; P = 0.003) and BFW (-15.7 versus -6.8 mm; P = 0.002) compared with placebo. The improvements in QOS and BFW were strongly correlated (Rval = 0.77, P < 0.001) suggesting a beneficial treatment effect on the restorative value of sleep. These results were confirmed in a subgroup of patients with a greater symptom severity. There was no evidence of rebound insomnia or withdrawal effects following treatment discontinuation. The incidence of adverse events was low and most side-effects were judged to be of minor severity. PR-melatonin is the first drug shown to significantly improve quality of sleep and morning alertness in primary insomnia patients aged 55 years and older-suggesting more restorative sleep, and without withdrawal symptoms upon discontinuation.

The effects of one night of sleep deprivation on known-risk and ambiguous-risk decisions.

Abstract: Sleep deprivation has been shown to alter decision-making abilities. The majority of research has utilized fairly complex tasks with the goal of emulating 'real-life' scenarios. Here, we use a Lottery Choice Task (LCT) which assesses risk and ambiguity preference for both decisions involving potential gains and those involving potential losses. We hypothesized that one night of sleep deprivation would make subjects more risk seeking in both gains and losses. Both a control group and an experimental group took the LCT on two consecutive days, with an intervening night of either sleep or sleep deprivation. The control group demonstrated that there was no effect of repeated administration of the LCT. For the experimental group, results showed significant interactions of night (normal sleep versus total sleep deprivation, TSD) by frame (gains versus losses), which demonstrate that following as little as 23 h of TSD, the prototypical response to decisions involving risk is altered. Following TSD, subjects were willing to take more risk than they ordinarily would when they were considering a gain, but less risk than they ordinarily would when they were considering a loss. For ambiguity preferences, there seems to be no direct effect of TSD. These findings suggest that, overall, risk preference is moderated by TSD, but whether an individual is willing to take more or less risk than when well-rested depends on whether the decision is framed in terms of gains or losses.

Heritability of diurnal type: a nationwide study of 8753 adult twin pairs

Abstract: Twin studies suggest a genetic component in diurnal types. In 1981, a questionnaire sent to the Older Finnish Twin Cohort yielded responses from 2836 adult monozygotic (MZ) and 5917 like-sexed dizygotic (DZ) twin pairs with four category self-report on diurnal type. We used structural equation modelling to estimate genetic and environmental components of variance in morningness and eveningness. The model fitting was best when the morningness and the eveningness were analysed together. The ADE-model (including additive genetic, dominant genetic and non-shared environmental effects) fitted best to the data. ADE-models for men and women separately did not differ in a statistically significant manner from the combined model, and similarly ADE-models for young and old age groups separately did not differ either. The estimate for overall genetic effect (broad sense heritability) was 49.7% (95% confidence interval 46.4-52.8), with the remainder accounted for by environmental factors not shared by siblings. The variance component estimates for the underlying liability to diurnal type were 11.7% (95% CI 0-23.7) for additive genetic factors, 38.0% (24.7-51.3) for genetic factors due to dominance. Genetic effects thus account for about one-half of the interindividual variability in diurnal type in adults.

Trait interindividual differences in the sleep physiology of healthy young adults

Abstract: Summary Despite decades of sleep research by means of polysomnography (PSG), systematic interindividual differences in PSG-assessed sleep parameters have been scarcely investigated. The present study is the first to quantify interindividual variability in standard PSG-assessed variables of sleep structure in terms of stability and robustness as well as magnitude. Twenty-one carefully screened healthy young adults were studied continuously in a strictly controlled laboratory environment, where their PSGs were recorded for eight nights interspersed with three separate 36 h sleep deprivation periods. All PSG records were scored blind to subject and condition, using conventional criteria, and delta power in the non-REM sleep EEG was computed for four electrode derivations. Interindividual differences in sleep variables were examined for stability and robustness, respectively, by comparing results across equivalent nights (e.g. baseline nights) and across experimentally differentiated nights (baseline nights versus recovery nights following sleep deprivation). Among 18 sleep variables analyzed, all except slow-wave sleep (SWS) latency were found to exhibit significantly stable and robust – i.e. trait-like – interindividual differences. This was quantified by means of intraclass correlation coefficients (ICCs), which ranged from 36% to 89% across physiologic variables, and were highest for SWS (73%) and delta power in the non-REM sleep EEG (78–89%). The magnitude of the trait interindividual differences was considerable, consistently exceeding the magnitude of the group-average effect on sleep structure of 36 h total sleep deprivation. Notably, for non-REM delta power – a putative marker of sleep homeostasis – the interindividual differences were from 9.9 to 12.8 times greater than the group-average increase following sleep deprivation relative to baseline. Physiologic sleep variables did not vary among subjects in a completely independent manner – 61.1% of their combined variance clustered in three trait dimensions, which appeared to represent sleep duration, sleep intensity, and sleep discontinuity. Any independent functional significance of these sleep physiologic phenotypes remains to be determined.

Improving actigraphic sleep estimates in insomnia and dementia: How many nights?

Abstract: In order to investigate how the duration of actigraphic recordings affects the reliability of actigraphic estimates of sleep and 24-h activity rhythm variables, two to 3 weeks of actigraphy were recorded, from which pairs of variables derived from two periods of increasing length (1-10 days) were compared. Two groups were studied: (1) 10 subjects suffering from primary insomnia; and (2) 12 demented elderly subjects living semi-independently in group care facilities of homes for the elderly. Actigraphic estimates of primary measures of sleep (duration and efficiency) and of the 24-h activity pattern (interdaily stability, intradaily variability and amplitude) were calculated on variable lengths of the actigraphic recordings. The average absolute difference of two estimates decreased - and reliability increased - strongly with an increasing number of days analysed. An acceptable reliability of the interdaily stability estimate required more than 7 days of recording. It can be concluded that a valuable improvement in the reliability of actigraphic sleep estimates can be obtained by simply increasing the number of recording nights. The results support the importance of day-to-day variability in insomnia and dementia that has already been previously noted by others, and even suggest the presence of 'week-to-week' variability. This variability may have been involved in the equivocal results of treatment studies in insomnia and dementia where outcome measures were based on a limited number of nights. Such studies could profit from extension of the recording duration to, e.g. 2 weeks, and from the inclusion of variability measures as measures of clinical interest.

Validation of actigraphy for determining sleep and wake in children with sleep disordered breathing.

Abstract: Summary There have been limited studies of the validation of actigraphy for the determination of sleep and wake in children and in this study we aimed to compare wrist actigraphy with polysomnography (PSG). We studied 45 children (29 M/16 F), aged between 1 and 12 years (5.8 ± 2.7 years, mean ± SD). Actigraphic data were collected during standard overnight PSG. Data from the actiwatch were analysed over four separate activity threshold settings (low, medium, high, auto). Actigraphic data were compared epoch-by-epoch with the matching PSG. Sleep time was not different from PSG values for the low or auto activity thresholds, but was significantly less on the medium and high activity thresholds (P < 0.05). In contrast, the low and auto activity thresholds significantly underestimated wake time (P < 0.05), whilst that recorded on the medium and high activity thresholds were not different to PSG values. Agreement rates across the thresholds were all high ranging from 85.1% to 88.6%. Predictive value for sleep and sensitivity were also high with values ranging from 91.6% to 94.9% and 90.1% to 97.7%, respectively. In contrast, predictive value for wake and specificity were low ranging between 46.7–65.6% and 39.4–68.9%, respectively. There was no effect of subject age, OAHI or PSG arousal index on AR for any of the activity thresholds. We conclude that actigraphy is a reliable method for determining sleep in children when compared against PSG. Actigraphy may be a useful tool in paediatric sleep clinics and research.

Robust circadian rhythm in heart rate and its variability: influence of exogenous melatonin and photoperiod

Abstract: Summary Heart rate (HR) and heart rate variability (HRV) undergo marked fluctuations over the 24-h day. Although controversial, this 24-h rhythm is thought to be driven by the sleep–wake/rest–activity cycle as well as by endogenous circadian rhythmicity. We quantified the endogenous circadian rhythm of HR and HRV and investigated whether this rhythm can be shifted by repeated melatonin administration while exposed to an altered photoperiod. Eight healthy males (age 24.4 ± 4.4 years) participated in a double-blind cross-over design study. In both conditions, volunteers were scheduled to 16 h–8 h rest : wake and dark : light cycles for nine consecutive days preceded and followed by 29-h constant routines (CR) for assessment of endogenous circadian rhythmicity. Melatonin (1.5 mg) or placebo was administered at the beginning of the extended sleep opportunities. For all polysomnographically verified wakefulness periods of the CR, we calculated the high- (HF) and low- (LF) frequency bands of the power spectrum of the R–R interval, the standard deviation of the normal-to-normal (NN) intervals (SDNN) and the square root of the mean-squared difference of successive NN intervals (rMSSD). HR and HRV variables revealed robust endogenous circadian rhythms with fitted maxima, respectively, in the afternoon (16:36 hours) and in the early morning (between 05:00 and 06:59 hours). Melatonin treatment phase-advanced HR, HF, SDNN and rMSSD, and these shifts were significantly greater than after placebo treatment. We conclude that endogenous circadian rhythmicity influences autonomic control of HR and that the timing of these endogenous rhythms can be altered by extended sleep/rest episodes and associated changes in photoperiod as well as by melatonin treatment.

Adverse childhood experiences associated with sleep in primary insomnia.

Abstract: The objectives were to explore the association between self-reported adverse childhood experiences (ACE) and sleep in adults suffering from primary insomnia and to examine the impact of presleep stress on this relationship. Fifty-nine patients with primary insomnia, aged 21-55 years, were administered the Childhood Trauma Questionnaire (CTQ) and then divided into two groups according to the achieved scores: with moderate/severe or low/no reports of ACE. The participants spent three consecutive nights in the sleep laboratory in order to record polysomnographic and actigraphic sleep parameters. A stress induction technique was administered by activating negative autobiographical memories immediately before sleep in the second or third night. Results show that 46% of the insomniac patients reported moderate to severe ACE. This group exhibited a significantly greater number of awakenings and more movement arousals compared to patients with low or no reports of ACE. Actigraphic data also indicated more disturbed sleep and increased nocturnal activity for the high-ACE group. On the other hand, no specific group differences were found with regard to stress condition. The results support the assumption that it is possible to identify a subgroup among patients with primary insomnia who has experienced severe maltreatment in childhood and adolescence. This subgroup appears to differ in several sleep parameters, indicating a more disturbed sleep compared to primary insomniacs with low or no reports of ACE. With regard to sleep-disturbing nightly patterns of arousal, parallels between individuals with high ACE and trauma victims as well as post-traumatic stress disorder-patients suggest themselves.

The use of actigraphy for assessment of the development of sleep/wake patterns in infants during the first 12 months of life.

Abstract: Maturation of sleep/wake patterns is one of the most important physiological developments during the first year of life. In this study, we aimed to compare the use of actigraphy and parental sleep diaries (SD) for recording the development of sleep/wake patterns longitudinally in term infants in their own home environments over the first 12 months of life. Twenty healthy term infants (7F/13M) were studied for 3 days each month in their own homes over the first 12 months of life. Sleep/wake patterns were recorded using both SD and actigraphy (AW) (AW64, Mini Mitter Co. Inc., Sunriver, OR, USA). The development of sleep and wake was analysed over 24 h, during the day (08:00-20:00 hours) and during the night (20:00-08:00 hours). A total of 186 studies had complete data sets for both analysis methods. Overall, there was no difference between methods of measurement for determination of the total percentage of sleep or wake over 24 h, or for the total percentage of sleep or wake during the day. However, at night, AW scored less time asleep (73.3 +/- 0.9%) and more time awake (26.7 +/- 0.9%) compared with the SD (80.7 +/- 1.04% and 19 +/- 1.0%, respectively, P < 0.001). Mean percentage sleep during the day decreased from 51% at 1 month to 28% at 12 months with the 1-month values being significantly higher than all other ages, while mean percentage sleep at night was only different between 1 month and 11 and 12 months. In conclusion actigraphy provides a useful tool for assessing the development infant sleep.

Mood changes after sleep deprivation in morningness-eveningness chronotypes in healthy individuals.

Abstract: Inconsistent results have been found in the studies evaluating the effect of both total and partial sleep deprivation (SD) on mood in healthy subjects and a few variables have been analyzed as possible predictors. In the present study, we examined whether circadian preference modifies the effect of SD on mood changes in healthy subjects. Sample consisted of 60 healthy volunteers (including 30 morningness and 30 eveningness subjects). Then, the two groups were again divided into two groups for two SD procedures. Fifteen morningness and 15 eveningness chronotypes were total sleep deprived and 15 morningness and 15 eveningness subjects were partial sleep deprived. The mood changes were evaluated before and after SD using Profile of Mood States. Two main results were obtained from our study: a significant increase in depression subscale in morningness chronotypes and a significant decrease in depression subscale score after total SD (TSD) in eveningness chronotypes. The changes in depression-dejection scores of eveningness chronotypes after total (P < 0.01) and partial SD (P < 0.01) were significantly different from changes in morningness chronotypes after TSD. Our results suggest that the effect of SD on mood in normal subjects is related to their circadian preferences. The morningness or eveningness characteristics of the shift workers have significant impact on their mood states. Therefore, adjusting the work schedule with the morningness and eveningness characteristics of the workers may improve their mood alterations.

Stability of genetic influence on morningness-eveningness: a cross-sectional examination of South Korean twins from preadolescence to young adulthood.

Abstract: A cross-sectional twin design was used to study the developmental nature of genetic and environmental influences on morningness-eveningness (M-E). A total of 977 South Korean twin pairs aged 9-23 years completed 13 items of a Korean version of the Composite Scale through the telephone interview. The total sample was split into three age groups: preadolescents, adolescents, and young adults. Twin correlations did not vary significantly with age, suggesting that genetic influences on M-E are stable throughout the developmental span. Results of model-fitting analyses indicated that genetic and environmental factors explained, respectively, 45% and 55% of the variance in all three age groups. Environmental factors were primarily those factors that twins did not share as a consequence of their common rearing; family environmental factors in M-E were consistently near zero in all three age groups. The present study is the first to demonstrate genetic influences on M-E in preadolescent children as young as 9 years old. In spite of differences in culture and frequencies of genes between South Koreans and Caucasians, genetic and environmental influences on M-E found in the present sample were remarkably similar to those reported by previous studies on the basis of late adolescent and adult Caucasian twins.

Predicting long-term sickness absence from sleep and fatigue.

Abstract: Disturbed or shortened sleep is prospectively related to disease. One might also expect that sickness absence would be another consequence but very little data seem to exist. The present study used 8300 individuals in a national sample to obtain information on reports of disturbed sleep and fatigue one [corrected] year and merged this with data on long-term sickness absence two [corrected] years later. A logistic regression analysis was applied to the data with adjustments for demographic and work environment variables. The results showed that individuals without registered sickness absence at the start had a higher probability of entering a period of long-term (>/=90 days, odds ratio [OR] = 1.24 with 95% Confidence Interval [CI] = 1.09[corrected]-2.18[corrected]) sickness absence two [corrected] years later if they reported disturbed sleep at the start. The value [corrected] for fatigue was OR = 1.69[corrected] (CI = 1.23[corrected]-2.33[corrected]). When fatigue or disturbed sleep was separately excluded the OR increased to OR = 1.90[corrected] and OR = 1.86[corrected], respectively. Intermediate sickness absence (14-89 days) showed similar but slightly weaker results. The results indicate that disturbed sleep and fatigue are predictors of long-term absence and it is suggested that impaired sleep may be part of a chain of causation, considering its effects on fatigue.

Pulsed radio‐frequency electromagnetic fields: dose‐dependent effects on sleep, the sleep EEG and cognitive performance

Abstract: To establish a dose-response relationship between the strength of electromagnetic fields (EMF) and previously reported effects on the brain, we investigated the influence of EMF exposure by varying the signal intensity in three experimental sessions. The head of 15 healthy male subjects was unilaterally exposed for 30 min prior to sleep to a pulse-modulated EMF (GSM handset like signal) with a 10 g-averaged peak spatial specific absorption rate of (1) 0.2 W kg(-1), (2) 5 W kg(-1), or (3) sham exposed in a double-blind, crossover design. During exposure, subjects performed two series of three computerized cognitive tasks, each presented in a fixed order [simple reaction time task, two-choice reaction time task (CRT), 1-, 2-, 3-back task]. Immediately after exposure, night-time sleep was polysomnographically recorded for 8 h. Sleep architecture was not affected by EMF exposure. Analysis of the sleep electroencephalogram (EEG) revealed a dose-dependent increase of power in the spindle frequency range in non-REM sleep. Reaction speed decelerated with increasing field intensity in the 1-back task, while accuracy in the CRT and N-back task were not affected in a dose-dependent manner. In summary, this study reveals first indications of a dose-response relationship between EMF field intensity and its effects on brain physiology as demonstrated by changes in the sleep EEG and in cognitive performance.

Age-related change in the association between a polymorphism in the PER3 gene and preferred timing of sleep and waking activities.

Abstract: The objective of this study was to investigate the effect of age on the association between preferred timing of sleep and waking activities and a coding-region variable number tandem repeat (VNTR) polymorphism in the clock gene PER3. We have previously reported this polymorphism to associate with diurnal preference and delayed sleep phase syndrome (DSPS). Participants (n = 1590; 707 males and 883 females) completed the Horne-Ostberg (HO) questionnaire for diurnal preference and provided a DNA sample. Overall HO scores were plotted against age. The 5% extremes and intermediates were selected for genotyping. Frequencies of the PER3 4- and 5-repeat alleles were examined in separate age groups (18-29, 30-39, 40-49 and 50+ years of age). The 4-repeat allele was significantly more frequent in evening types, and the 5-repeat allele more frequent in morning types (Fisher's exact test, P = 0.016). Analysis in the four age groupings revealed that the strength of this association attenuated with age and was significant only in the youngest group (18-29 years). These results extend our previous finding of an association between the PER3 VNTR and diurnal preference. They also demonstrate that diurnal preference in young people is more closely associated with this polymorphism than it is in other age groups.

Daytime sleepiness, exercise, and physical function in older adults.

Abstract: The purpose of this study was to describe the association between sleepiness, exercise, and physical function in older adults, testing the hypothesis that sleepiness predicts decreased exercise and impaired physical function in this population. We performed a secondary analysis of data from the National Sleep Foundation's Sleep in America Poll, comparing frequency of exercise and ability to perform functional tasks between sleepy and non-sleepy subjects. Trained interviewers administered a scripted telephone survey. Participants (n = 1506) were community-dwelling older Americans (55-84 years) randomly chosen from geographically representative households with listed telephone numbers. Sleepiness 'so severe that it interferes with daytime activity' was dichotomized as 'daily/frequently' or 'never/rare'. Exercise frequency was scored 1-4 ('less than once a week' to 'more than five times a week'). Responses to five questions (walk 0.5 mile, climb stairs, push/pull heavy object, stoop/crouch/or kneel, write, handle small objects), rated 1-5 ('no difficulty' to 'unable to do'), were summed; a mean score of > or = 2.5 was considered impaired physical function. Daytime sleepiness predicted low exercise frequency while controlling for age and body mass index (BMI) (OR = 1.40, 95% CI 1.031-1.897, P = 0.031). Frequent daytime sleepiness predicted impaired physical function (OR = 2.76, 95%CI = 0.237-0.553, P = 0.001) after controlling for age, BMI, income and number of co-morbid conditions. The conclusion was that daytime sleepiness in older adults is associated with physical functional impairments and decreased exercise frequency. The findings suggest that sleepiness in older adults is not benign but has implications for continued physical decline and warrants attention.

Association of Type D personality to perceived side effects and adherence in CPAP-treated patients with OSAS.

Abstract: Continuous positive airway pressure (CPAP) is the treatment of choice for obstructive sleep apnoea syndrome (OSAS), but side effects are common and long-term adherence low. The Type D (distressed) personality is defined as a combination of negative affectivity and social inhibition. The association of Type D personality with adherence has not been studied in CPAP-treated patients with OSAS. This study aimed to describe the prevalence of Type D personality in OSAS patients with CPAP treatment longer than 6 months and the association with self-reported side effects and adherence. A cross-sectional descriptive design was used. A total of 247 OSAS patients with a mean use of CPAP treatment for 55 months (6-182 months) were included. Data collection was achieved by two questionnaires; the Type D scale 14 (DS14) (Type D personality), SECI (side effects of CPAP), as well as from medical records (clinical variables and objective adherence to CPAP treatment). Type D personality occurred in 30% of the patients with OSAS and significantly (P < 0.05-0.001) increased the perceived frequency and severity of a broad range of side effects. The objective adherence was significantly lower (P < 0.001) for OSAS patients with Type D compared to OSAS patients without Type D, both with regard to a mean use of 4 h per night and 85% of the self-rated sleep time per night. The additional effect of a Type D personality on perceived side effects and adherence to CPAP treatment found in this study could be used by healthcare personnel when evaluating patients waiting for treatment.

Mortality risk factors in sleep apnoea: a matched case-control study.

Abstract: Sleep apnoea syndrome was reported to be associated with increased mortality but it is not known if this association is independent of obesity and co-morbidities. The present study investigated predictors of mortality in a large cohort of men with sleep apnoea using a case-control design. The study population consisted of 10,981 men diagnosed during 1991-2000 by whole-night polysomnography with sleep apnoea; 331 men died prior to 1 September 2001, of whom 277 were matched by age, gender, site and time of study to patients who were alive in September 2001. Multivariate analysis revealed that all-cause mortality was associated with chronic obstructive pulmonary disease (COPD) (odds ratio, OR: 7.07, 95% CI 2.75-18.16), chronic heart failure (CHF) (OR: 5.47, 95% CI 1.06-28.31), diabetes mellitus (DM) (OR: 3.30, 95% CI 1.51-7.20) and body mass index (BMI) (increase of 5 kg m(-2), OR: 1.44, 95% CI: 1.04-1.99). Chronic upper airway problems were associated with survival (OR: 0.45, 95% CI 0.23-0.90). There were significant interactions between respiratory disturbance index and BMI and COPD. Mortality of patients younger than the median age (62 years) was associated with COPD, DM and an interaction between BMI and apnoea severity. Predictors of mortality for the older patients were COPD, CHF and DM. We conclude that all-cause mortality in sleep apnoea is associated with co-morbidities and obesity. Severity of sleep apnoea affects mortality by interacting with obesity and lung disease.

The effect of short‐term withdrawal from continuous positive airway pressure therapy on sympathetic activity and markers of vascular inflammation in subjects with obstructive sleep apnoea

Abstract: Obstructive sleep apnoea (OSA) is commonly associated with cardiovascular disease and sympathetic activation. However, it is unclear whether this association is independent of obesity and to what extent treatment with nasal continuous positive airway pressure (CPAP) alleviates the vascular inflammation that underpins cardiovascular disease. We therefore evaluated whether short-term withdrawal from CPAP therapy in subjects with moderate-severe OSA would result in increased levels of sympathetic activity and circulating inflammatory cytokines independent of weight. Vascular inflammatory markers (hsCRP, hsIL-6 and hsTNF-alpha) were assessed in 20 subjects after one and seven nights of withdrawal from CPAP together with the hypoxia-responsive angiogenic marker VEGF and urinary catecholamines. Compared with baseline on CPAP, withdrawal from therapy resulted in an immediate return of OSA with an increase in RDI to 26.7 +/- 5.2 and 39.0 +/- 5.9 events per hour after one and seven nights without CPAP, respectively (both P 0.1). In conclusion, 1 week of CPAP withdrawal was associated with a return of OSA and a marked increase in sympathetic activity without a concomitant elevation of vascular inflammatory markers.

Periodic leg movements during sleep and wakefulness in narcolepsy

Abstract: The objectives of the study were to measure the prevalence of periodic leg movements during NREM and REM sleep (PLMS) and while awake (PLMW) and to assess the impact of PLMS on nocturnal sleep and daytime functioning in patients with narcolepsy. One hundred and sixty-nine patients with narcolepsy and 116 normal controls matched for age and gender were included. Narcoleptics with high and low PLMS indices were compared to assess the impact of PLMS on sleep and Multiple Sleep Latency Test (MSLT) variables. More narcoleptics than controls had a PLMS index greater than 5 per hour of sleep (67% versus 37%) and an index greater than 10 (53% versus 21%). PLMS indices were higher both in NREM and REM sleep in narcoleptic patients, but the between-group difference was greater for REM sleep. A significant increase of PLMS index was also found with aging in both narcoleptic patients and controls. PLMW indices were also significantly higher in narcoleptic patients. Patients with an elevated index of PLMS had a higher percentage of stage 1 sleep, a lower percentage of REM sleep, a lower REM efficiency and a shorter MSLT latency. The present study demonstrates a high frequency of PLMS and PLMW in narcolepsy, an association between the presence of PLMS and measures of REM sleep and daytime functioning disruption. These results suggest that PLMS represent an intrinsic feature of narcolepsy.

The relationship between craniofacial anatomy and obstructive sleep apnoea: a case-controlled study.

Abstract: The aim of the study was to identify craniofacial and pharyngeal anatomical factors directly related to obstructive sleep apnoea (OSA). The design and setting was a hospital-based, case-controlled study. Ninety-nine subjects (78 males and 21 females) with a confirmed diagnosis of OSA, who were referred to the Dental Hospital for construction of a mandibular advancement splint were recruited. A similar number of control subjects, matched for age and sex, were recruited after completing snoring and Epworth Sleepiness Scale questionnaires to exclude habitual snoring and daytime sleepiness. An upright cephalogram was obtained and skeletal and soft tissue landmarks were traced and digitized. In OSA subjects the anteroposterior skeletal measurements, including maxillary and mandibular length were reduced (P < 0.001). The intermaxillary space was found to be 3.1 mm shorter in OSA subjects (P = 0.001). The nasopharyngeal airway in OSA subjects was narrower (P < 0.001) but pharyngeal length showed no difference. The tongue size was increased (P = 0.021), soft plate length, thickness and area were all greater (P < 0.001) and the hyoid bone was more inferiorly positioned in OSA subjects (P < 0.001). This study identifies a significant number of craniofacial and pharyngeal anatomical factors directly related to OSA.

The dynamics of neurobehavioural recovery following sleep loss

Abstract: Rate of recovery of daytime performance and sleepiness following moderate and severe sleep deprivation (SD) was examined when recovery opportunity was either augmented or restricted. Thirty healthy non-smokers, aged 18-33 years, participated in one of three conditions: moderate SD with augmented (9-h) recovery opportunities, moderate SD with restricted (6-h) recovery opportunities, or severe SD with augmented recovery opportunities. Each participant attended the laboratory for 8-9 consecutive nights: an adaptation and baseline night (23:00-08:00 hours), one or two night(s) of wakefulness, and five consecutive recovery sleep opportunities (23:00-08:00 hours or 02:00-08:00 hours). On each experimental day, psychomotor vigilance performance (PVT) and subjective sleepiness (SSS) were assessed at two-hourly intervals, and MSLTs were performed at 1000 h. PSG data was collected for each sleep period. For all groups, PVT performance significantly deteriorated during the period of wakefulness, and sleepiness significantly increased. Significant differences were observed between the groups during the recovery phase. Following moderate SD, response speed, lapses and SSS returned to baseline after one 9-h sleep opportunity, while sleep latencies required two 9-h opportunities. When the recovery opportunity was restricted to six hours, neither PVT performance nor sleepiness recovered, but stabilised at below-baseline levels. Following severe SD, sleepiness recovered after one (SSS) or two (physiological) 9-h sleep opportunities, however PVT performance remained significantly below baseline for the entire recovery period. These results suggest that the mechanisms underlying the recovery process may be more complicated than previously thought, and that we may have underestimated the impact of sleep loss and/or the restorative value of subsequent sleep.

Measurement properties and hierarchical item structure of the Epworth Sleepiness Scale in Parkinson's disease

Abstract: The aim of this work was to evaluate the measurement properties and hierarchical item structure of the Epworth Sleepiness Scale (ESS) in patients with Parkinson's disease (PD). Data were taken from a cross-sectional study regarding fatigue and sleep-related aspects of PD. One hundred and eighteen consecutive patients with neurologist-diagnosed PD without significant co-morbidities (54% men; mean age, 64 years; mean PD duration, 8.4 years) from four Swedish neurological outpatient clinics participated. The ESS displayed good data quality with few missing items (0-2.5%): good reliability (Cronbach's alpha, 0.84), marginal floor and no ceiling effects (1.7% and 0% respectively), and differentiated between those reporting problems staying awake during the past month and those who did not. Item-total correlations, factor and Rasch analyses indicated that items tap a single underlying construct. Rasch analysis supported basic rating scale assumptions and demonstrated an item hierarchy similar to that previously found in patients with other sleep disorders. Gaps in the levels of sleep propensity covered by ESS items and their response options were identified at the higher and lower ends of the underlying sleepiness continuum. This study provides an evidence base for using the ESS in PD by demonstrating good psychometric properties and a stable hierarchical item structure. However, addition of new items and use of Rasch scoring has potential to further enhance the clinical usefulness of the ESS.

Alcohol-induced sleepwalking or confusional arousal as a defense to criminal behavior: a review of scientific evidence, methods and forensic considerations.

Abstract: Summary An increasing number of criminal cases have claimed the defendant to be in a state of sleepwalking or related disorders induced by high quantities of alcohol Sleepwalkers who commit violent acts, sexual assaults and other criminal acts are thought to be in a state of automatism, lacking conscious awareness and criminal intent They may be acquitted in criminal trials On the other hand, criminal acts performed as the result of voluntary alcohol intoxication alone cannot be used as a complete defense The alcohol-induced sleepwalking criminal defense is most often based on past clinical or legal reports that ingestion of alcohol directly ‘triggers’ sleepwalking or increased the risk of sleepwalking by increasing the quantity of slow wave sleep (SWS) A review of the sleep medicine literature found no sleep laboratory studies of the effects of alcohol on the sleep of clinically diagnosed sleepwalkers However, 19 sleep laboratory studies of the effects of alcohol on the sleep of healthy non-drinkers or social drinkers were identified with none reporting a change in SWS as a percentage of total sleep time However, in six of 19 studies, a modest but statistically significant increase in SWS was found in the first 2–4 h Among studies of sleep in alcohol abusers and abstinent abusers, the quantity and percentage of SWS was most often reduced and sometimes absent Claims that direct alcohol provocation tests can assist in the forensic assessment of these cases found no support of any kind in the medical literature with not a single report of testing in normative or patient groups and no reports of validation testing of any sort There is no direct experimental evidence that alcohol predisposes or triggers sleepwalking or related disorders A legal defense of sleepwalking resulting from voluntarily ingested alcohol should be consistent with the current state of art sleep science and meet generally accepted requirements for the diagnosis of sleepwalking and other parasomnias

Sleep related rhythmic movement disorder revisited.

Abstract: Summary To classify sleep related rhythmic movement disorder (SRMD) based on clinical, polysomnographic and videometric evaluation in a predominantly adult population, twenty-four patients (four females) aged 11–67 years identified by polysomnography and videometry were classified for type of SRMD, its duration and frequency during wakefulness and in the different sleep stages. SRMD persisted unto child- and adulthood in all patients. SRMD is not restricted to sleep-wake transition, occurs most frequently in wake, stages NREM 1 and 2, but also in REM and slow wave sleep. Most patients have one form of SRMD, few have two forms in one night. Longest duration is in wakefulness. Duration does not differ from one sleep cycle to another. Sleep is not fragmented by SRMD, and sleep stages generally do not change when SRMD occurs. Only few patients have short awakenings after SRMD. In four patients with sleep apnea SRMD coincided frequently with the onset of the apnea related arousal. Two patients had a family history of SRMD. In contrast to the ICSD-2 SRMD seems to persist into adulthood frequently with male preponderance. Familial forms are rare. SRMD in the investigated population is always occurring during sleep, even if patients reported it to occur strictly at wake-sleep transition. Polysomnography is a useful method to uncover SRMD aggravated by other sleep disorders and allows insight in some aspects of the pathology of this disorder, which is not well understood. In the adult patients it is not associated with mental pathologies and can be triggered by sleep apnea.

Determinants of excessive daytime sleepiness in a French community-dwelling elderly population.

Abstract: SUMMARY Epidemiological studies have suggested that excessive daytime sleepiness (EDS) is associated with depression, but the association between EDS and other psychiatric disorders has not been investigated. The aim of this study was to investigate the association of EDS with a wide range of psychiatric disorders and health-related conditions in the elderly population. Two thousand two hundred and fifty-nine noninstitutionalised persons aged 65-years and over randomly recruited from the Montpellier district, France, completed the Epworth Sleepiness Scale (ESS). Psychiatric status was assessed by the Mini International Neuropsychiatric Interview and demographic and other health information was obtained. This cross-sectional study was conducted from March 1999 to February 2001. Men were significantly more likely to report EDS (ESS score>10) compared with women (12.0% versus 6.0% respectively). EDS was significantly associated in univariate analyses with chronic diseases, early awakening, snoring, severity of depression and lifetime prevalence of manic and hypomanic episodes. A multivariate analysis revealed that the lifetime prevalence of manic and hypomanic episodes, snoring and gender (male) were independently associated with EDS. No independent association with other psychiatric disorders was found.

Children's sleep and adjustment: the moderating role of vagal regulation.

Abstract: Children's vagal tone and vagal suppression were examined as moderators of associations between children's sleep disruptions and adjustment problems. A relatively large sample (n = 167) of boys and girls who ranged in age between 8 and 9 years participated with their parents. Sleep was examined via actigraphy in the child's home for seven consecutive days. Children's vagal tone was examined during baseline conditions, and their vagal suppression was assessed in response to an inter-adult argument. In comparison with children exhibiting higher levels of vagal tone, those with lower vagal tone were at increased risk of externalizing problems, depression symptoms and higher body mass index associated with increased sleep disruptions (i.e. lower Sleep Efficiency, increased Wake Minutes and fewer Sleep Minutes). Thus, lower vagal tone functioned as a vulnerability factor for adjustment problems in the context of sleep problems. A higher level of vagal suppression to the inter-adult argument functioned as a protective factor against externalizing behaviors otherwise associated with increased Wake Minutes and reduced Sleep Efficiency. Findings demonstrating the moderating role of vagal functioning in the context of sleep disruptions are novel, and highlight the importance of individual differences in children's physiological regulation for sleep and adjustment.

Train driving efficiency and safety: examining the cost of fatigue

Abstract: This study investigated the effects of fatigue on train driving using data loggers on 50 locomotives operated by pairs of male train drivers (24-56 years) on an Adelaide-Melbourne corridor. Drivers' work history was used to calculate a fatigue score using Fatigue Audit Interdyne Software. Trains were assigned to one of three groups, based on drivers' maximum fatigue score: low (n = 15), moderate (n = 22) or high (n = 13) fatigue. Changes in driving parameters at different fatigue levels were investigated. A significant (P < 0.05) increase in fuel use was observed. Drivers in the moderate fatigue group used 4% more, and drivers in the high group used 9% more fuel than drivers in the low group. As these trains run daily, taking horsepower into account, this represents an approximate extra weekly cost of AUD$3512 using high compared with low fatigue drivers. High fatigue-group drivers used less throttle and dynamic brake and engaged in more heavy brake and maximum speed violations. Comparison of three, 100 km track sub-sections with undulating, flat, and hilly grade indicated that fuel use increases occurred primarily during the undulating sub-section, and heavy brake and maximum speed violations occurred primarily in the flat sub-section. Fatigued driving becomes less well-planned, resulting in reduced efficiency (e.g. increased fuel consumption) and safety (e.g. braking and speeding violations). Fatigue may manifest differentially depending on track grade. In certain areas, fatigue will cause increased fuel use and economic cost, and in others, reduced safety through driving violations. These factors should be carefully examined in future railway operator research.