Showing papers in "Sleep in 1998"

Adolescent Sleep Patterns, Circadian Timing, and Sleepiness at a Transition to Early School Days

Abstract: Study Objectives: This study examined effects on adolescent sleep patterns, sleepiness, and circadian phase of a school transition requiring an earlier start. Design and Setting: Adolescents were evaluated in 9th and 10th grades; school start time in 9th grade was 0825 and in 10th grade was 0720. Assessments at each point included 2 weeks of actigraphy and sleep diaries at home, followed by a 22-hour laboratory evaluation, including evening saliva samples every 30 minutes in dim light for determination of dim-light salivary melatonin onset phase (DLSMO), overnight sleep monitoring, and multiple sleep latency test (MSLT). Participants: Twenty-five females and 15 males, ages 14 to 16.2 were enrolled; 32 completed the study in 9th grade and 26 completed in 10th grade. Interventions: Participants kept their own schedules, except that laboratory nights were scheduled based upon school-night sleep pattems. Measurements and Results: According to actigraphy, students woke earlier on school days in 10th than in 9th grade, but they did not go to sleep earlier and they slept less. DLSMO phase was later in 10th grade (mean = 2102) than 9th grade (mean = 2024). Sleep latency on MSLT overall was shorter in 10th (mean = 8.5 minutes) than in 9th (mean = 11. 4 minutes), particularly on the first test of the moming at 0830 (5.1 vs 10.9 minutes). Two REM episodes on MSLT occurred in 16% of participants in 10th grade; one REM episode occurred in 48%. When those with REM sleep on one or both morning MSLTs (n=11) were compared to those without morning REM, significant differences included shorter sleep latency on the first test, less slow wave sleep the night before, and later DLSMO phase in those who had morning REM. Conclusions: Early start time was associated with significant sleep deprivation and daytime sleepiness. The occurrence of REM sleep on MSLT indicates that clinicians should exercise caution in interpreting MSLT REM sleep in adolescents evaluated on their usual schedules. Psychosocial influences and changes in bioregulatory systems controlling sleep may limit teenagers' capacities to make adequate adjustments to an early school schedule.

A CLOCK Polymorphism Associated with Human Diurnal Preference

Abstract: A single nucleotide polymorphism located in the 3' flanking region of the human CLOCK gene was investigated as a predictor of diurnal preference in a population-based random sample of 410 normal adults. Morningness-eveningness preferences were determined using the 19-item Horne-Ostberg questionnaire. Subjects carrying one of the two CLOCK alleles, 3111C, had a significantly lower mean Horne-Ostberg score. The distribution of scores was clearly shifted toward eveningness for these subjects. The score difference was independent of age, sex and ethnic heritage, thus making population stratification effects unlikely to explain this difference. These subjects had a substantial 10- to 44-minute delay in preferred timing for activity or sleep episodes. We suggest that the identified polymorphism or another tightly linked polymorphism within the CLOCK gene or its regulatory elements may be responsible for the finding.

Methods for obtaining and analyzing unattended polysomnography data for a multicenter study

Abstract: Summary: This paper reviews the data collection, processing, and analysis approaches developed to obtain comprehensive unattended polysomnographic data for the Sleep Heart Health Study, a multicenter study of the cardiovascular consequences of sleep-disordered breathing. Protocols were developed and implemented to standardize in-home data collection procedures and to perform centralized sleep scoring. Of 7027 studies performed on 6 697 participants, 5 534 studies were determined to be technically acceptable (failure rate 5.3%). Quality grades varied over time, reflecting the influences of variable technician experience, and equipment aging and modifications. Eighty-seven percent of studies were judged to be of igoodi quality or better, and 75% were judged to be of sufficient quality to provide reliable sleep staging and arousal data. Poor submental EMG (electromyogram) accounted for the largest proportion of poor signal grades (9% of studies had <2 hours artifact free EMG signal). These data suggest that with rigorous training and clear protocols for data collection and processing, good-quality multichannel polysomnography data can be obtained for a majority of unattended studies performed in a research setting. Data most susceptible to poor signal quality are sleep staging and arousal data that require clear EEG (electroencephalograph) and EMG signals.

Iron and the Restless Legs Syndrome

Abstract: STUDY OBJECTIVES Using blinded procedures, determine the relation between serum ferritin levels and severity of subjective and objective symptoms of the restless legs syndrome (RLS) for a representative patient sample covering the entire adult age range. DESIGN All patient records from the past 4 years were retrospectively reviewed to obtain data from all cases with RLS. All patients were included who had ferritin levels obtained at about the same time as a polysomnogram (PSG), met diagnostic criteria for RLS, and were not on iron or medications that would reduce the RLS symptoms at the time of the PSG. SETTING Sleep Disorders Center. PATIENTS 27 (18 females, 9 males), aged 29-81 years. INTERVENTIONS None. MEASUREMENTS AND RESULTS Measurements included clinical ratings of RLS severity and PSG measures of sleep efficiency and periodic limb movements (PLMS) in sleep with and without arousal. Lower ferritin correlated significantly to greater RLS severity and decreased sleep efficiency. All but one patient with severe RLS had ferritin levels < or = 50 mcg/l. Patients with lower ferritin (< or = 50 mcg/l) also showed significantly more PLMS with arousal than did those with higher ferritin, but the PLMS/hour was not significantly related to ferritin. This last finding may be due to inclusion of two 'outliers' or because of severely disturbed sleep of the more severe RLS patients. CONCLUSIONS These data are consistent with those from a prior unblinded study and suggest that RLS patients will have fewer symptoms if they have ferritin levels greater than 50 mcg/l.

Cognitive function following acute sleep restriction in children ages 10-14.

Abstract: STUDY OBJECTIVES: Various aspects of human performance were assessed in children after sleep loss PARTICIPANTS: Sixteen children (7 males, 9 females) between the ages of 10 and 14 years DESIGN AND INTERVENTIONS: Children were randomly assigned to either a control (CTRL) group, with 11 hours in bed, or an experimental sleep restriction (SR) group, with 5 hours in bed, on a single night in the sleep laboratory MEASUREMENTS: Both groups were evaluated the following day with a battery of performance and sleepiness measures Psychomotor and cognitive performance tests were given during four 1-hour testing sessions at 2-hour intervals RESULTS: A multiple sleep latency test (MSLT) documented shorter latencies for SR children than controls Significant treatment differences were discovered in three of four variables of verbal creativity, including fluency, flexibility, and average indices There were also group differences found on the Wisconsin Card Sorting Test (WCST), which may be indicative of difficulty learning new abstract concepts Measures of rote performance and less-complex cognitive functions, including measures of memory and learning and figural creativity, did not show differences between groups, perhaps because motivation could overcome sleepiness-related impairment for these tasks CONCLUSIONS: Higher cognitive functions in children, such as verbal creativity and abstract thinking, are impaired after a single night of restricted sleep, even when routine performance is relatively maintained Language: en

Reliability of scoring respiratory disturbance indices and sleep staging.

Abstract: Study Objectives: Unattended, home-based polysomnography (PSG) is increasingly used in both research and clinical settings as an alternative to traditional laboratory-based studies, although the reliability of the scoring of these studies has not been described The purpose of this study is to describe the reliability of the PSG scoring in the Sleep Heart Health Study (SHHS), a multicenter study of the relation between sleep-disordered breathing measured by unattended, in-home PSG using a portable sleep monitor, and cardiovascular outcomes Design: The reliability of SHHS scorers was evaluated based on 20 randomly selected studies per scorer, assessing both interscorer and intrascorer reliability Results: Both inter- and intrascorer comparisons on epoch-by-epoch sleep staging showed excellent reliability (kappa statistics >080), with stage 1 having the greatest discrepancies in scoring and stage 3/4 being the most reliably discriminated The arousal index (number of arousals per hour of sleep) was moderately reliable, with an intraclass correlation (ICC) of 054 The scorers were highly reliable on various respiratory disturbance indices (RDls), which incorporate an associated oxygen desaturation in the definition of respiratory events (2% to 5%) with or without the additional use of associated EEG arousal in the definition of respiratory events (ICC>090) When RDI was defined without considering oxygen desaturation or arousals to define respiratory events, the RDI was moderately reliable (ICC=074) The additional use of associated EEG arousals, but not oxygen desaturation, in defining respiratory events did little to increase the reliability of the RDI measure (ICC=077) Conclusions: The SHHS achieved a high degree of intrascorer and interscorer reliability for the scoring of sleep stage and RDI in unattended in-home PSG studies

Correlates of daytime sleepiness in 4578 elderly persons: The cardiovascular health study

Abstract: Objectives: To describe the prevalence of self-reported daytime sleepiness in older men and women and to describe their relationships with demographic factors, nocturnal complaints, health status, and cardiovascular diseases (CVD). Design: Cross-sectional survey and clinical exam. Setting: Participants in the Cardiovascular Health Study, 4578 adults aged 65 and older, recruited from a random sample of non-institutionalized Medicare enrollees in four U.S. communities. Measures: Daytime sleepiness measured by the Epworth Sleepiness Scale (ESS), magnetic resonance imaging of the brain (MRI), cognitive function tests, and standardized questionnaires for cardiopulmonary symptoms and diseases, depressive symptoms, social support, activities of daily living, physical activity, and current medications. Results: Approximately 20% of the participants reported that they were usually sleepy in the daytime. Although elderly black men were less likely to report frequent awakenings than those in the other three race and gender groups, they had significantly higher mean ESS scores. The following were independently associated with higher ESS scores in gender-specific models: non-white race, depression, loud snoring, awakening with dyspnea or snorting, frequent nocturnal awakenings, medications used to treat congestive heart failure, non-use of sleeping pills, a sedentary lifestyle, and limitation of activities of daily living in both men and women; additional correlates included hip circumference and current smoking in men, and hayfever in women. The following were not independently associated with ESS in the models: age, education, use of wine or beer to aid sleep, use of tricyclic antidepressants, long- or short-acting benzodiazepines, asthma, angina, myocardial infarction, congestive heart failure itself, forced vital capacity, social support, cognitive function, or MRI evidence of global brain atrophy or white matter abnormality. Conclusions: Daytime sleepiness is common in the elderly, probably due to nocturnal disturbances such as frequent awakenings and snoring. The occasional use of sleeping pills for insomnia is associated with reduced daytime sleepiness in the elderly, while the use of medications for congestive heart failure is associated with daytime sleepiness. Surprisingly, anatomic abnormalities such as evidence of previous strokes and brain atrophy (as seen on brain MRI scans) were not associated with daytime sleepiness in these non-institutionalized elderly persons.

Interrelations between sleep and the somatotropic axis

Abstract: In the human as in other mammals, growth hormone (GH) is secreted as a series of pulses. In normal young adults, a major secretory episode occurs shortly after sleep onset, in temporal association with the first period of slow-wave (SW) sleep. In men, approximately 70% of the daily GH output occurs during early sleep throughout adulthood. In women, the contribution of sleep-dependent GH release to the daily output is lower and more variable. Studies involving shifts of the sleep-wake cycle have consistently shown that sleep-wake homeostasis is the primary determinant of the temporal organization of human GH release. Effects of circadian rhythmicity may occasionally be detected. During nocturnal sleep, the sleep-onset GH pulse is caused by a surge of hypothalamic GHRH release which coincides with a circadian-dependent period of relative somatostatin disinhibition. Extensive evidence indicates the existence of a consistent relationship between SW sleep and increased GH secretion and, conversely, between awakenings and decreased GH release. There is a linear relationship between amounts of SW sleep--whether measured by visual scoring or by delta activity--and amounts of concomitant GH secretion, although dissociations may occur, most likely because of variable levels of somatostatin inhibition. Pharmacological stimulation of SW sleep results in increased GH release, and compounds which increase SW sleep may therefore represent a novel class of GH secretagogues. During aging, SW sleep and GH secretion decrease with the same chronology, raising the possibility that the peripheral effects of the hyposomatotropism of the elderly may partially reflect age-related alterations in sleep-wake homeostasis. While the association between sleep and GH release has been well documented, there is also evidence indicating that components of the somatotropic axis are involved in regulating sleep. The studies are most consistent in indicating a role for GHRH in promoting NREM and/or SW sleep via central, rather than peripheral, mechanisms. A role for GH in sleep regulation is less well-documented but seems to involve REM, rather than NREM, sleep. It has been proposed that the stimulation of GH release and the promotion of NREM sleep by GHRH are two separate processes which involve GHRH neurons located in two distinct areas of the hypothalamus. Somatostatinergic control of GH release appears to be weaker during sleep than during wake, suggesting that somatostatinergic tone is lower in the hypothalamic area(s) involved in sleep regulation and sleep-related GH release than in the area controlling daytime GH secretion. While the concept of a dual control of daytime and sleep-related GH secretion remains to be directly demonstrated, it allows for the reconciliation of a number of experimental observations.

Epidemiology of alcohol and medication as aids to sleep in early adulthood

Abstract: Study objectives In a representative sample of adults 18-45 years of age, this study addressed three questions about the use of sleep aids in the general population: (1) what are the past-year prevalences of the use of alcohol, over-the-counter medication and prescription medication to facilitate sleep? (2) among those who use these substances for sleep problems, what are the patterns of use? and (3) are there social factors, independent of sleep characteristics, that increase the likelihood of alcohol and medication use to aid sleep? Design The 1996 Detroit Area Survey was a random-digit-dial, computer-assisted survey of a representative sample of 2,181 adults ages 18-45 in the Detroit primary metropolitan statistical area. Eligible household response rate was 86.8%. Results In the general population, use of alcohol and medication as sleep aids in the past year was found to be fairly common: 13% used alcohol, 18% used medications and 5% used both. The prevalence of any substance use to aid sleep was 26%. The duration of use was short for the majority of users, less than 1 week. However, duration of use was greater for the majority of those using prescription sleep aids. A substantial minority of users report regular use lasting longer than 1 month: 15%, 9%, and 36% for alcohol, OTC medications, and prescription medications, respectively. Both sociodemographic and sleep characteristics were associated with alcohol and medication use to aid sleep. Difficulty falling asleep was the factor most strongly associated with use of substances to improve sleep. Sex, race/ethnicity, work shift, marital status and education were also significantly associated with one or more types of sleep aid use adjusting for difficulty falling asleep.

Starting times of school: effects on daytime functioning of fifth-grade children in Israel.

Abstract: In the present study we investigated the effects of school starting time on daytime behavior and sleep. Eight-hundred and eleven 5th grade pupils (10-12 years old) from 28 classes in 18 schools throughout Israel were divided into "early risers" (N = 232) who started school at 07:10 (42%) at least 2 times a week, and "regular risers" (N = 340) who always started school at 08:00 (58%). The remaining 239 pupils started school between 7:20 and 07:55 (and also after 08:00), and were not included in the study. Self-administered questionnaires concerning sleep habits during school days, weekends, and holidays, daytime fatigue, sleepiness, and difficulties concentrating and paying attention in school were completed by all children. Mean sleep time of the "early risers" was significantly shorter than that of the "regular risers." Early risers complained significantly more about daytime fatigue and sleepiness, and about attention and concentration difficulties in school. Their complaints were independent of the reported hours of sleep. We conclude that early starting of school negatively affects total sleep time and, as a consequence, has a negative effect on daytime behavior. The implications of these findings to the ongoing controversy concerning sleep need in contemporary society are discussed.

Effect of age on EEG arousals in normal sleep.

Abstract: EEG arousals were quantified in 40 nocturnal polysomnographic recordings belonging to four age groups (teenagers: 10 to 19 years; young adults: 20 to 39 years; middle-aged: 40 to 59 years; elderly: > or = 60 years). Ten subjects (five males and five females) participated in each group. The subjects were healthy and sound sleepers. All sleep recordings were preceded by an adaptation night which aimed at excluding the presence of sleep-related disorders. The recordings were carried out in a partially soundproof recording chamber and in a standard laboratory setting. Arousal indices (AI), defined as the number of arousals per hour of sleep, were calculated for total sleep time (AI/TST) and for all the sleep stages. AI/TST increased linearly with age (r = 0.852; p < 0.00001): teenagers (13.8), young adults (14.7), middle-aged (17.8), elderly (27.1). An age-related positive linear correlation was found also for the arousal indices referred to NREM sleep (r = 0.811; p < 0.00001) and to stages 1 and 2 (r = 0.712; p < 0.00001), while in stages 3 and 4 and in REM sleep, arousal indices showed stable values across the ages. Overall, arousals lasted 14.9 +/- 2.3 seconds, with arousal duration stable across the ages (range of means: 13.3-16.6 seconds) and no relevant differences between NREM sleep (14.6 +/- 2.5 seconds) and REM sleep (16.2 +/- 5 seconds). The paper discusses the impact of age on arousals, the similarities between arousals and the phases d'activation transitoire, and the consideration that arousals are physiological components of sleep.

The Role of Melatonin and Circadian Phase in Age-related Sleep-maintenance Insomnia: Assessment in a Clinical Trial of Melatonin Replacement

Abstract: The present investigation used a placebo-controlled, double-blind, crossover design to assess the sleep-promoting effect of three melatonin replacement delivery strategies in a group of patients with age-related sleep-maintenance insomnia. Subjects alternated between treatment and "washout" conditions in 2-week trials. The specific treatment strategies for a high physiological dose (0.5 mg) of melatonin were: (1) EARLY: An immediate-release dose taken 30 minutes before bedtime; (2) CONTINUOUS: A controlled-release dose taken 30 minutes before bedtime; (3) LATE: An immediate-release dose taken 4 hours after bedtime. The EARLY and LATE treatments yielded significant and unambiguous reductions in core body temperature. All three melatonin treatments shortened latencies to persistent sleep, demonstrating that high physiological doses of melatonin can promote sleep in this population. Despite this effect on sleep latency, however, melatonin was not effective in sustaining sleep. No treatment improved total sleep time, sleep efficiency, or wake after sleep onset. Likewise, melatonin did not improve subjective self-reports of nighttime sleep and daytime alertness. Correlational analyses comparing sleep in the placebo condition with melatonin production revealed that melatonin levels were not correlated with sleep. Furthermore, low melatonin producers were not preferentially responsive to melatonin replacement. Total sleep time and sleep efficiency were correlated with the timing of the endogenous melatonin rhythm, and particularly with the phase-relationship between habitual bedtime and the phase of the circadian timing system.

Cognitive executive dysfunction in patients with obstructive sleep apnea syndrome (OSAS) after CPAP treatment.

Abstract: We have previously described impairments of cognitive executive functions in 17 patients with OSAS in comparison with 17 normal controls, as assessed by various frontal-lobe-related tests In the present study, 10 of these OSAS patients treated with continuous positive airway pressure (CPAP) were reevaluated after 4-6 months of treatment Neuropsychological tasks explored attention, short-term memory span, learning abilities, planning capacities, categorizing activities, and verbal fluency Patients were found to have normalized most of their cognitive executive and learning disabilities, but all the short-term memory tests remained unchanged These findings are discussed in light of the contribution of the frontal-lobe-related systems to short-term memory functions, and the eventual pathogenic role played by sleep fragmentation and nocturnal hypoxemia, which are related to the occurrence of apneic and hypopneic events In conclusion, short-term memory impairment was persistent in OSAS patients despite CPAP treatment for 4-6 months

Treatment of obstructive sleep apnea syndrome by rapid maxillary expansion.

Abstract: The precise role of maxillary constriction in the pathophysiology of obstructive sleep apnea (OSA) is unclear However, it is known that subjects with maxillary constriction have increased nasal resistance and resultant mouth-breathing, features typically seen in OSA patients Maxillary constriction is also associated with alterations in tongue posture which could result in retroglossal airway narrowing, another feature of OSA Rapid maxillary expansion (RME) is an orthodontic treatment for maxillary constriction which increases the width of the maxilla and reduces nasal resistance The aim of this pilot study was to investigate the effect of rapid maxillary expansion in OSA We studied 10 young adults (8 male, 2 female, mean age 27 +/- 2 [sem] years) with mild to moderate OSA (apnea/hypopnea index-AHI 19 +/- 4 and minimum SaO2 89 +/- 1%), and evidence of maxillary constriction on orthodontic evaluation All patients underwent treatment with RME, six cases requiring elective surgical assistance Polysomnography was repeated at the completion of treatment Nine of the 10 patients reported improvements in snoring and hypersomnolence There was a significant reduction in AHI (19 +/- 4 vs 7 +/- 4, p < 005) in the entire group In seven patients, the AHI returned to normal (ie, = < 5); only one patient showed no improvement These preliminary data suggest that RME may be a useful treatment alternative for selected patients with OSA

Evaluation "in-car" countermeasures to sleepiness: cold air and radio.

Abstract: The efficacy of putative"in-car"countermeasures to driver sleepiness is unknown. Sixteen young adult drivers within the normal range for the Epworth Sleepiness Scale (ESS), had their sleep restricted to 5 hours the night before, and drove an interactive car simulator in the afternoon for 2.5 hours, under monotonous conditions. After 30 minutes of driving they were exposed to: (1) cold air to the face (AIR) from the vehicle's air conditioning vents, (2) listening to the vehicle's radio/tape (RADIO) according to subjects' choice, or (3) NIL treatment. The active treatments typified those experienced under real driving conditions. Drifting over lane markings were"incidents."EEGs were recorded and spectrally analyzed in the alpha and theta range. Subjects responded to the Karolinska Sleepiness Scale (KSS) every 200 seconds. Overall, RADIO and AIR had no significant effects on incidents, although there was a trend for RADIO to reduce incidents, particularly during the first 30 minutes, when AIR also had some effect. KSS scores were significantly lower for RADIO for most of the drive, whereas AIR had only transient and non-significant effects. The EEG showed no significant effects of the active treatments. Compared with other countermeasures such as caffeine and a brief nap, which we have previously shown to be more effective (using the same equipment and protocols), AIR and RADIO are at best only temporary expedients to reduce driver sleepiness, perhaps enabling drivers to find a suitable place to stop, take a break and avail themselves of caffeine and a nap. Language: en

Sleep-disordered breathing and self-reported general health status in the Wisconsin Sleep Cohort Study

Abstract: Objective: To determine the relationship between sleep-disordered breathing and self-reported general health status. Design: Cross sectional, population-based study of general health status, satisfaction with life, and sleep-disordered breathing status assessed by overnight in-laboratory polysomnography. Setting: General Community Subjects: Employed men (n=421) and women (n=316), ages 30-60 years, enrolled in the Wisconsin Sleep Cohort Study Interventions: None Outcome Measure: Self-reported general health profile and life satisfaction measured by the Medical Outcomes Survey Short Form-36 and obtained by interview. Results: Sleep-disordered breathing was associated with lower general health status before and after adjustment for age, sex, body mass index, smoking status, alcohol usage, and a history of cardiovascular conditions. Even mild sleep-disordered breathing (apnea-hypopnea index = 5) was associated with decrements in the Medical Outcomes Short Form 36 Survey health constructs comparable to the magnitude of decrements linked to other chronic conditions such as arthritis, angina, hypertension, diabetes, and back problems. Conclusions: Sleep-disordered breathing is independently related to lower general health status, and this relationship is of clinical significance. Given the growing emphasis of the importance of patients' perceptions of health, these findings are relevant to estimating the overall impact of sleep-disordered breathing.

Pupillographic assessment of sleepiness in sleep-deprived healthy subjects.

Abstract: Spontaneous pupillary-behavior in darkness provides information about a subject's level of sleepiness. In the present work, pupil measurements in complete darkness and quiet have been recorded continuously over 11-minute period with infrared video pupillography at 25 Hz. The data have been analyzed to yield three parameters describing pupil behavior; the power of diameter variation at frequencies below 0.8 Hz (slow changes in pupil size), the pupillary unrest index, and the average pupil size. To investigate the changes of these parameters in sleep deprivation, spontaneous pupillary behavior in darkness was recorded every 2 hours in 13 healthy subjects from 19:00 to 07:00 during forced wakefulness. On each occasion, comparative subjective sleepiness was assessed with a self-rating scale (Stanford Sleepiness Scale, SSS). The power of slow pupillary oscillations (< or = 0.8 Hz) increased significantly and so did the values of SSS, while basic pupil diameter decreased significantly. Slow pupillary oscillations and SSS did not correlate well in general but high values of pupil parameters were always associated with high values in subjective rating. Our results demonstrate a strong relationship between ongoing sleep deprivation and typical changes in the frequency profiles of spontaneous pupillary oscillations and the tendency to instability in pupil size in normals. These findings suggest that the results of pupil data analysis permit an objective measurement of sleepiness.

Pharmacokinetics of gammahydroxybutyrate (GHB) in narcoleptic patients

Abstract: Sodium gammahydroxybutyrate (GHB) is an endogenous compound that has been under investigation in the management of narcolepsy for about two decades. The data confirm that GHB treatment decreases daytime sleepiness and episodes of cataplexy, sleep paralysis, and hypnagogic hallucinations. The current study evaluated the pharmacokinetics of GHB, given twice in one night to six narcoleptic patients who had been chronically taking GHB nightly on a similar basis. Results confirmed earlier reports and showed nonlinear pharmacokinetics. Maximum concentrations were reached in 40 +/- 6.2 and 35.7 +/- 7 minutes after the first and second dose respectively. Mean AUCinf was 17731.6 +/- 4867 mg/mL/m. Mean GHB T1/2 was 53 +/- 19 minutes. GHB elimination appears to be capacity-limited in some patients when administered at a fixed dose of 3 g twice nightly at a 4-hour interval.

Interactive effects of sleep deprivation, time of day, and driving experience on a driving task

Abstract: Performance decrements after more than 24 hours of sleep deprivation (SD) are not only a monotonic function of the duration of SD, but are the result of an interaction between SD and time of day. The major deteriorations in performance during SD are still evident throughout the night, as in the non-sleep-deprived state. Twelve experienced and 12 inexperienced drivers drove a driving simulator for 20 minutes at 0800, 1100, 1400, 1700, and 2000 hours on two testing days. One testing day was conducted after a normal night's sleep, and the other after one night of SD. Reaction time (RT) was also measured while driving. The standard deviation of both lateral position and speed were significantly higher during SD. Performance steadily improved across the day between 0800 and 2000 hours, and the absence of any sleep-by-time interactions suggests that the rhythm of driving performance across the day was similar after both normal sleep and SD. Inexperienced drivers had higher RTs than experienced drivers in both sleep-deprived and non-sleep-deprived conditions. These results have important implications for those involved in the transport industry.

Effect of NMDA lesion of the medial preoptic neurons on sleep and other functions.

Abstract: This study was undertaken to determine the effects of the destruction of the medial preoptic area (mPOA) neurons by N-methyl D-aspartic acid (NMDA), on sleep-wakefulness (S-W), locomotor activity, body weight, rectal temperature, and food and water intake in rats. The NMDA lesion of the mPOA produced long-lasting insomnia with marked reduction in the deeper stages of sleep, including paradoxical sleep. The reduction in the duration of sleep episodes in the lesioned rats indicated their inability to maintain sleep. The insomnia resulting from a decreased sleep pressure did not alter the sleep-initiating ability. Though the day-night distribution of sleep remained largely unaffected, there was an increase in locomotor activity during the light period. There was no increase in food intake to compensate for the high energy expenditure resulting not only from hyperactivity but also from hyperthermia in the mPOA-lesioned rats. Thus, body weights of the rats were reduced even without any change in food and water intake. However, the changes in body temperature and locomotor activity after the mPOA neuronal loss may not have exerted a major influence on S-W, as the alterations in all these parameters had different time courses.

Magnesium therapy for periodic leg movements-related insomnia and restless legs syndrome: an open pilot study

Abstract: Periodic limb movements during sleep (PLMS), with or without symptoms of a restless legs syndrome (RLS), may cause sleep disturbances. The pharmacologic treatments of choice are dopaminergic drugs. Their use, however, may be limited due to tolerance development or rebound phenomena. Anecdotal observations have shown that oral magnesium therapy may ameliorate symptoms in patients with moderate RLS. We report on an open clinical and polysomnographic study in 10 patients (mean age 57 +/- 9 years; 6 men, 4 women) suffering from insomnia related to PLMS (n = 4) or mild-to-moderate RLS (n = 6). Magnesium was administered orally at a dose of 12.4 mmol in the evening over a period of 4-6 weeks. Following magnesium treatment, PLMS associated with arousals (PLMS-A) decreased significantly (17 +/- 7 vs 7 +/- 7 events per hour of total sleep time, p < 0.05). PLMS without arousal were also moderately reduced (PLMS per hour of total sleep time 33 +/- 16 vs 21 +/- 23, p = 0.07). Sleep efficiency improved from 75 +/- 12% to 85 +/- 8% (p < 0.01). In the group of patients estimating their sleep and/or symptoms of RLS as improved after therapy (n = 7), the effects of magnesium on PLMS and PLMS-A were even more pronounced. Our study indicates that magnesium treatment may be a useful alternative therapy in patients with mild or moderate RLS-or PLMS-related insomnia. Further investigations regarding the role of magnesium in the pathophysiology of RLS and placebo-controlled studies need to be performed.

Full Polysomnography in the Home

Abstract: Study Objectives: To evaluate unattended full polysomnography (PSG) recorded in the home by the DigiTrace Home Sleep System (DHSS) and to assess the ability to acquire, store and analyze polysomnographic data using the DHSS compared to standard paper PSG. Design: Part 1 used a prospective, cross-over design. Part 2 consisted of a prospective concurrent collection of polysomnographic data. Setting: Sleep Disorders Center in a university medical center. Participants: All adult patients who required standard clinical PSG as part of their clinical evaluation, regardless of suspected diagnosis, except patients requiring video recording for abnormal behaviors. Measurements and Results: The DHSS is a digital recording system with miniature preamplifiers and the capacity to record 18 channels of polysomnographic data, including 4 channels of EEG (C 3 -A 2 , C 4 -A 1 , C 3 -O 1 and C 4 -O 2 ), right and left EOG, two channels of chin EMG, ECG naso-oral airflow, respiratory effort (piezo crystal thoracic and abdominal belts and bilateral intercostal EMG), snore microphone, bilateral anterior tibialis EMG, and body-position sensor. In part 1, 77 DHSS home recordings were evaluated. No recordings were lost due to equipment failure and each parameter was scorable in greater than 95% of all epochs. Most of the subjective assessments by questionnaire following each study revealed no difference between the two testing situations. However, patients reported more sleep time and a better overall test experience in the lab. Assessments of sleep quality and morning alertness compared to usual were rated higher in the lab. After completing both studies, more patients preferred the lab study (p <.01), mostly because of minor inconveniences and apprehension regarding acquisition of data during the home study. There was no difference in the assessment of which test most accurately represented their sleep. In Part 2, the DHSS recorded concurrently with paper PSG in the laboratory in 16 patients. The results show no significant differences for any parameter and strong positive correlations for all parameters. Conclusion: Using the DHSS, unattended full PSG can be performed in the home with reliable and high quality recordings. Full PSG can be extended to a larger patient population, because it is no longer limited by the number of beds, and there is a reduction in cost due to elimination of overnight staff and facility cost.

Long-term facilitation of ventilation in humans during NREM sleep.

Abstract: The purpose of this study was to determine whether episodic hypoxic exposure would elicit long term facilitation (LTF) of ventilation (V(I)) in sleeping humans. Twenty subjects gave written informed consent. Of these, six subjects were unable to maintain stable stage 2 sleep or deeper for a majority of the experiment and their data were excluded from the analysis. On night 1 after subjects had reached stable sleep (stage 2 or deeper), the subjects breathed room air for 5 minutes, followed by 3 minutes of hypoxia (F(I)O2 = 8%). This sequence was repeated 10 times, and the breathing pattern was observed for a further 60 minutes. Subjects returned to the laboratory for a second visit, which served as a sham night. Instrumentation and study time were the same as on night 1, but subjects breathed room air only. Airflow, tidal volume (V(T)), end tidal O2 and CO2, and estimation of arterial O2 saturation (%) were measured. Seven of the subjects had long-term facilitation (LTF), which was manifested as a significant increase in V(I) that persisted for up to 40 minutes following the last hypoxic exposure. In the other seven subjects, no substantial increase in V(I) was found. We could not explain this difference based on body size (BMI), gender, level of hypoxemia, or magnitude of the hyperpnea during hypoxia. The difference between the two groups was that the LTF group consisted of habitual snorers, and that the NLTF were not inspiratory-flow-limited during the experiment.

Sleepiness as Measured by Modified Multiple Sleep Latency Testing Varies as a Function of Preceding Activity

Abstract: Many studies have examined the impact of varying levels of sleep loss or sleep disturbance upon the multiple sleep latency test (MSLT). Virtually no studies have examined the impact of level of physiologic arousal upon measured sleep tendency. In the current study, 12 normal-sleeping young adults took modified multiple sleep latency tests after either watching television for 15 minutes or after a 5-minute walk. This entire protocol was repeated on another week after subjects had been partially sleep deprived by reducing their time in bed by 50%. It was hypothesized that sleep latencies would be significantly shorter after watching television as compared to walking and after partial sleep loss as compared to normal sleep and that these effects would be independent. The results of the study supported all of these hypotheses. ANOVAs showed no significant interaction effects, but sleep latencies were 11.6 and 5.8 minutes following the walk and watching television respectively. Sleep latencies were 9.8 and 7.6 minutes following baseline and partial sleep-deprivation conditions. Heart rate, used as a measure of physiological arousal, was significantly elevated throughout naps following the walk as compared to naps following television viewing. On a theoretical level, these data imply that measured sleepiness is a combination of sleep drive and physiological arousal, and these effects appear to be independent. On a practical level, these data indicate that more care may be necessary in monitoring the activity levels of patients and subjects prior to MSLT evaluations, since physiological arousal may mask the measurement of sleep tendency. Knowledge of the role of arousal in modulating sleepiness can be important in many settings.

Medium-intensity light produces circadian rhythm adaptation to simulated night-shift work.

Abstract: STUDY OBJECTIVES To assess the effect of nocturnal light intensity on circadian adaptation to simulated night work. SETTING AND PARTICIPANTS Normal young men and women, simulated night work, home sleep. DESIGN AND MEASUREMENTS We compared temperature rhythm phase shifts following timed exposure to high (approximately 5700 lux 3 hours/day), medium (approximately 1230 lux 3 hours/day) or constant low-intensity (< 250 lux) light during consecutive night shifts. Subjects (n = 35) followed a schedule of 7 days baseline, 6 days of 8-hour night shifts (with day sleep delayed 10 hours from baseline sleep), and 4 days of recovery. Subjects wore dark sunglasses while outdoors during daylight. Sleep logs were completed after each 8-hour sleep/dark period. Night work fatigue was rated by questionnaire. RESULTS During the 3rd through 5th days of night work, most subjects in the high and medium groups (100% and 85%) exhibited phase delays large enough that their body temperature minima occurred within the daytime sleep/dark period. Only 42% of subjects in the low group exhibited phase delays large enough to meet this criterion of circadian adaptation. The phase shifts of the high and medium groups were not significantly different, and were significantly different from the low group. Larger phase shifts were correlated with more sleep and less fatigue. CONCLUSIONS Extremely "bright" light may not be necessary for circadian adaptation in shift work situations similar to our study protocol (e.g., regular daytime sleep/dark periods, sunglasses).

The Taskforce 2000 survey on medical education in sleep and sleep disorders.

Abstract: Previous research has shown evidence of a widening gap between scientific research and clinical teaching in sleep and sleep disorders. To address the deficiencies in current medical education in sleep, the Taskforce 2000 was established by the American Sleep Disorders Association. The present study was undertaken to assess the teaching activities, needs and interests of the membership of the two largest professional sleep societies (American Sleep Disorders Association and Sleep Research Society). Survey instruments included a brief, 5-item postcard survey, which was mailed to all members, followed by an in-depth, 34-item questionnaire, which was completed by 158 respondents from the intitial postcard survey (N = 808). Results indicated that the majority of respondents (65.2%) are currently involved in teaching sleep to medical students or postgraduate trainees, although the average amount of teaching time was only 2.1 hours for undergraduate and 4.8 hours for graduate education in sleep. Teaching of sleep laboratory procedures and clinical evaluation of sleep-disordered patients is limited at either an undergraduate or postgraduate level. The major deficiencies noted were the lack of time in the medical curriculum and the need for better resources and teaching facilities. A large majority of respondents indicated their willingness to be involved in sleep education for physicians, and rated this a high priority for the professional organization.

Sleep hygiene in physically dependent nursing home residents : Behavioral and environmental intervention implications

Abstract: The purpose of this report is to summarize data from a sample of 230 residents in eight nursing homes (NHs) that are relevant to the development of environmental and behavioral interventions for sleep. Four conclusions can be drawn: (1) there is strong evidence that the nighttime sleep of these residents was adversely affected by environmental noise and light; (2) residents appear to spend substantial time in bed and sleeping during the day; (3) there are significant differences between some homes in the amount of time that residents spend in bed and sleeping during the day, as well as the frequency of nighttime awakenings associated with environmental events; and (4) residents' preference and nighttime noise source data suggest that a multifaceted intervention to improve sleep hygiene could successfully implemented in the NH setting. An intervention addressing these issues may result in improved sleep and overall well-being for a substantial portion of the NH population.

Susceptibility of LDL to Oxidative Stress in Obstructive Sleep Apnea

Abstract: Cardiovascular diseases are more common in patients with obstructive sleep apnea (OSA) than in the general population. We hypothesized that severe hypoxemia during sleep in these patients may cause an imbalance between reactive oxygen species and the antioxidant reserve that is important for the detoxification of these molecules. We tested the hypothesis that low-density lipoproteins (LDL) in hypoxic OSA patients may be more susceptible to oxidative stress than LDL of nonhypoxic OSA patients and normal controls. Fifteen OSA patients were included in this study, six with severe hypoxia (hypoxic group) who spent more than 10 minutes during sleep with SaO 2 <85% (mean 96 minutes), and nine OSA patients (nonhypoxic group) who spent less than 10 minutes during sleep with SaO 2 <85% (mean 1.1 minutes). Six healthy non-smoking males of the same age group were included as a control group. The susceptibility of each individual's LDL to oxidative stress was examined after free-radical challenge in vitro by assessing changes in levels of conjugated dienes. The LDL in OSA patients with severe hypoxia was not more susceptible to oxidative stress compared to the LDL of nonhypoxic OSA patients and normal controls. After 6 hours of exposure to an oxidative agent, the changes in the mean conjugated diene were not different among the three groups (p = 0.75). The time required to reach 50% of maximal absorbance was also not different, p = 0.199. Glutathione peroxidase and catalase activities in red blood cells in the hypoxic and nonhypoxic patient groups were not significantly different. One night of CPAP therapy in each patient group did not significantly change the level of the antioxidant enzymes. Our results did not show any difference in the susceptibility to oxidative stress between hypoxic and nonhypoxic OSA patients and normal controls.

Sleep and pulmonary function in children with well-controlled, stable asthma.

Abstract: The aim of this study was to assess sleep and pulmonary function in asthmatic and control children. Forty children with well-controlled, stable asthma, and 34 controls (age range: 8.2 to 15.4 years) were monitored with wrist actigraphs and peak-flow meters for 3 consecutive days. In addition, asthma severity was assessed by subjective parental and self-rating scale and symptom checklist. Asthmatic children had poorer sleep quality in comparison to their controls, as manifested in lower percentages of quiet sleep (p < .05) and increased activity level during sleep (p < .05). As expected, asthmatic children had reduced morning peak expiratory flow measures (p < .01) and a higher evening-to-morning drop in peak expiratory flow (p < .005). Peak-flow measures were significantly correlated with subjective and objective sleep measures. In the asthmatic group, sleep measures were also correlated with subjective asthma severity indices and symptom checklists. We conclude that poorer sleep is associated with reduced pulmonary function. The reduced sleep quality, coupled with subjective reports of increased fatigue and reduced alertness found in asthmatic children, suggest that these children are at risk for developing neurobehavioral deficits associated with chronic sleep loss.

Importance of the pulse oximeter averaging time when measuring oxygen desaturation in sleep apnea

Abstract: The accuracy of pulse oximeters in measuring transient changes in oxygen saturation (SaO2) may be affected by the oximeter time response. The aim of this study was to assess the effect of modifying the pulse oximeter averaging time (T) on the measurement of SaO2 in patients with the sleep apnea-hypopnea syndrome (SAHS). Twelve patients with severe SAHS were studied during a nap with conventional oximeters: Ohmeda 3740 and Criticare 501. We compared the readings of each patient's oxygen desaturation measured simultaneously with two identical pulse oximeters. One oximeter was the control (T = 3 seconds), and in the other T was set from 3 seconds to 21 seconds. No significant differences in SaO2 were found when both oximeters were set to the same T (3 seconds). In contrast, increasing T to 12 seconds and 21 seconds in one of the oximeters resulted in considerable and significant differences in the measured SaO2: oxygen desaturation was underestimated by up to 60% when compared with the control. The misestimation of SaO2 induced by settings of T which are within the range selectable in conventional oximeters may be of epidemiological significance when pulse oximetry is used as a complementary diagnostic tool to classify sleep events in SAHS.