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PubMed2004

Sleep and reported daytime sleepiness in normal subjects: the Sleep Heart Health Study.

STUDY OBJECTIVES: To describe the distribution of nocturnal sleep characteristics and reports of daytime sleepiness in a large well-defined group of healthy adults. DESIGN: The Sleep Heart Health Study is a multicenter study examining sleep and cardiopulmonary parameters through nocturnal polysomnography in adults enrolled in geographically distinct cardiovascular cohorts. SETTING: Community setting. PARTICIPANTS: 470 subjects enrolled in the Sleep Heart Health Study (n = 6440) were selected as a 'normative' group based on screening of health conditions and daily habits that could interfere with sleep. MEASUREMENTS AND RESULTS: Home-based nocturnal polysomnography was obtained on all participants and centrally scored for sleep and respiratory parameters. Demographic and health-related data were obtained and updated at the time of the home visit. Sleep efficiency decreased by 1.6% for each 10 years of increased age. Sleep time decreased by 0.1 hours (6.0 minutes) for each 10-year age increase and was longer in women. The arousal index increased by 0.8 for each 10-year increase in age and was lower by 1.4 in women. Women had a lower mean percentage of stage 1 and stage 2 sleep. Mean percentage of slow-wave sleep was higher in women (by 6.7%). Percentage of slow-wave sleep decreased with increased age for men only (by 1.9% for each 10-year age change). CONCLUSIONS: Data suggest a clear lessening in the quantity and quality of sleep with age that appears to be more rapid in males compared to females.

Aged↗
PubMed1983

Recovery sleep following sleep deprivation in intact and suprachiasmatic nuclei-lesioned rats.

Recovery sleep was studied for 3-5 days following 24 h of sleep deprivation (TSD) in normal rats and in rats lacking circadian rhythms (CRs) of sleep because of prior lesioning of the suprachiasmatic nuclei (SCN). One group of lesioned rats was run in constant dim light. Another lesioned group and an intact group were run on a 12:12 dark-light schedule with TSD and recovery beginning at lights-off. All groups showed immediate rebounds of high-amplitude NREM sleep and paradoxical sleep, confined mostly to the first 12-18 h of recovery, and decreases in moderate and low-amplitude NREM sleep during the first 6-12 h of recovery. Thus, sleep stage rebound priorities were little affected by CRs. Total sleep rebound was initially greatest in intact rats, but limited mostly to the first 12 h of recovery. Total sleep rebound was distributed over a longer period in SCN rats, but total accumulated rebound was similar in all groups. Thus, CRs appear to modulate the timing but not the amount of accumulated total sleep rebound. Results were interpreted in terms of ceiling effects on total sleep, delayed rebounds, and competition between CRs and homeostatic recovery processes. Recovery sleep of lesioned rats on the dark-light schedule was marked by a transient diurnal rhythm.

Animals↗
PubMed2006

Difference in sleep regulation between morning and evening circadian types as indexed by antero-posterior analyses of the sleep EEG.

Circadian types classify individuals according to their preferred timing for activity and sleep, morning and evening types showing, respectively, early or late preferences. This characteristic has been associated with corresponding differences in circadian sleep propensity. In this study, quantitative analysis of the sleep EEG in antero-posterior derivations was used to test the hypothesis that morning and evening types differ not only in the circadian aspect of sleep regulation but also in the homeostatic aspect. Morning types and evening types (six men and six women per group, aged 19-34 years) were selected using the Morningness-Eveningness Questionnaire. They were studied by polysomnography according to their preferred sleep schedule. Spectral activity in four midline derivations (Fz, Cz, Pz, Oz) was calculated separately in nonrapid eye movement (NREM) sleep and in rapid eye movement (REM) sleep. In NREM sleep, morning types showed a steeper decrease of slow-wave activity (SWA; 1-5 Hz) per sleep cycle in the fronto-central derivations and a steeper increase in 13-14 Hz activity in the parieto-occipital derivations than did evening types. Nonlinear regression analysis revealed that the exponential decay rate of relative values of SWA in NREM sleep was faster in morning than evening types, in the frontal derivation. In REM sleep, morning types showed a steeper decrease of high sigma (14-16 Hz) and beta (16-24 Hz) activities across the night in centro-parietal derivations than did evening types. These results show for the first time a clear difference between morning types and evening types in homeostatic sleep regulation.

Adult↗
PubMed1997

Melatonin and S-20098 increase REM sleep and wake-up propensity without modifying NREM sleep homeostasis.

The pineal hormone melatonin has been implicated in the circadian regulation of sleep. In a crossover design, we investigated the effect of acute administration of 5 mg melatonin and a melatonin agonist (S-20098, 5 and 100 mg) in healthy young men when given 5 h before bedtime on sleep structure and electroencephalogram (EEG) power density. Each trial comprised a baseline, a treatment, and a posttreatment sleep episode. Relative to the placebo condition, all treatments phase advanced the core body temperature rhythm [Kräuchi, K., C. Cajochen, D. Möri, C. Hetsch, and A. Wirz-Justice. Sleep Res. 24: 526, 1995; and Kräuchi, K., C. Cajochen, D. Möri, and A. Wirz-Justice. Am. J. Physiol. 272 (Regulatory Integrative Comp. Physiol. 41): R1178-1188, 1997]. Rapid eye movement (REM) sleep was increased after both melatonin and S-20098. This increase in REM sleep was most pronounced in the first REM sleep episode. On the posttreatment night after melatonin and S-20098 administration, more wakefulness was present in the latter one-half of the sleep episode. EEG power density between 0.25 and 20 Hz during either non-REM (NREM) or REM sleep did not differ from placebo. Thus a single early evening dose of melatonin or the agonist S-20098 increases REM sleep propensity and advances sleep termination while, at the same time, the EEG in NREM sleep remains unaffected.

Acetamides↗
PubMed2002

Correlations using the NREM-REM sleep cycle frequency support distinct regulation mechanisms for REM and NREM sleep.

Polysomnograms of most homeothermic species distinguish two states, rapid eye movement (REM) and non-REM (NREM) sleep. These alternate several times during the night for reasons and following rules that remain poorly understood. It is unknown whether each state has its own function and regulation or whether they represent two facets of the same process. The present study compared the mean REM/NREM sleep ratio and the mean number of NREM-REM sleep cycles across 3 consecutive nights. The rationale was that, if REM and NREM sleep are tightly associated, their ratio should be comparable whatever the cycle frequency in the night. Twenty-six healthy subjects of both sexes were recorded at their home for 4 consecutive nights. The correlation between the REM/NREM sleep ratio and the number of cycles was highly significant. Of the two sleep components, REM sleep was associated to the number of cycles, whereas NREM sleep was not. This suggests that the relationship between REM sleep and NREM sleep is rather weak within cycles, does not support the concept of NREM-REM sleep cycles as miniature units of the sleep process, and favors the concept of distinct mechanisms of regulation for the two components.

Adolescent↗
PubMed2000

Sleep laboratory studies in restless legs syndrome patients as compared with normals and acute effects of ropinirole. 1. Findings on objective and subjective sleep and awakening quality.

Although the restless legs syndrome (RLS) is a disorder with a relatively high prevalence rate (8% in Austria) and leads to insomnia and excessive daytime tiredness, there is a paucity of sleep laboratory data concerning objective and subjective sleep and awakening quality. Thus, the aim of this study was to investigate 12 untreated RLS patients as compared with 12 normal controls and subsequently measure the acute effects of 0.5 mg ropinirole (Requip((R))) - a nonergoline dopamine agonist - as compared with placebo. In 3 nights (adaptation, placebo, ropinirole night) sleep induction, maintenance and architecture were measured objectively by polysomnography, subjective sleep and awakening quality were assessed by self-rating scales and visual-analog scales, and objective awakening quality was evaluated by a psychometric test battery. In polysomnography, RLS patients demonstrated, as compared with normal controls, a decreased total sleep time (TST) and sleep efficacy, increased wakefulness during the total sleep period and frequency of nocturnal awakenings, increased sleep stage S1, decreased S2 and increased stage shifts. Subjective sleep quality tended to decrease, and morning well-being, mood, affectivity and wakefulness were deteriorated. In the noopsyche, fine motor activity and reaction time performance were deteriorated. Ropinirole 0.5 mg induced, as compared with placebo, an increase in TST, sleep efficacy, S2 sleep and stage shifts. In the morning, somatic complaints increased slightly, while fine motor activity and reaction time performance improved. Our findings suggest a key-lock principle in the diagnosis/treatment of RLS and a dopaminergic mechanism in its pathogenesis, which is supported by the data on periodic leg movements during sleep and arousals of the subsequent paper.

Administration, Oral↗
PubMed2000

Pre-sleep cognitive activity: a comparison of sleep-onset insomniacs and good sleepers.

OBJECTIVE: Pre-sleep cognitive activity has been implicated in the maintenance of sleep-onset insomnia. The present study aimed to investigate the focus of attention, content and characteristics of cognition during the pre-sleep period. METHOD: A semi-structured clinician-administered interview designed to index the content of pre-sleep cognition was completed by individuals diagnosed with sleep-onset insomnia (N = 30) and good sleepers (N = 30). RESULT: The pre-sleep cognitive activity of insomniacs could be distinguished from that of good sleepers by being more focused on worries, problems and noises in the environment, and less focused on 'nothing in particular'. In terms of content, the insomnia group were more likely to think about not sleeping or about something that had happened during the day. Insomniacs experienced their pre-sleep cognitive activity as more occupying, less intentional, for a longer duration, and as causing more difficulty with sleep onset compared to good sleepers. Pre-sleep imagery was reported at similar rates across diagnosis, but was more distressing and more likely to be associated with strong physical sensations for the insomniac group compared with the good sleeper group. CONCLUSION: The present study provides a comprehensive investigation of pre-sleep cognitive activity and raises a number of areas for future research including monitoring of bodily sensations, imagery, problem-solving and non-active strategies in facilitating sleep onset.

Adult↗
PubMed2000

Sleep homeostasis and the function of sleep.

A considerable number of hypothetical functions of sleep have been proposed, but none of the hypotheses under active consideration has gained enough experimental support to convince a preponderance of sleep researchers. Some researchers even question whether we should expect to identify one primary function of sleep, given the multitude of physiological processes that are affected by sleep. But we do know that sleep is homeostatically regulated, and we have discovered a great deal about the physiological mechanisms underlying sleep homeostasis. Other homeostatically regulated behaviors have one or a small number of functions, and those functions are closely linked to the homeostatic control mechanisms for those process. We can therefore apply what is already known about sleep homeostasis to test and evaluate hypothesized functions of sleep. It should be possible to trace the connections between the cellular and molecular basis of a hypothesized function and the cellular and molecular mechanisms underlying homeostatic responses to sleep deprivation. Hypothesized functions that do not plausibly admit of such connections can reasonably be rejected. Four current hypotheses suggesting that the function of sleep is to assist in the process of activity-dependent synaptic reorganization are critiqued to demonstrate how what is known about sleep homeostasis can be used to assess hypothesized functions of sleep.

Brain↗
PubMed1999

[Effects of sleep stage on blood pressure and heart rate in patients with obstructive sleep apnea syndrome].

OBJECTIVE: To determine the effects of sleep stage on blood pressure(BP) and heart rate(HR) and to explore the relationship between BP and HR in patients with obstructive sleep apnea syndrome (OSAS). METHODS: Manometric tube was retained in the radial artery, and whole-night polysomnography (PSG) was done synchronously in 13 patients with OSAS. RESULTS: (1) The increase in BP during apnea was higher in REM sleep than in NREM sleep, but the difference was not significant (P > 0.05). When BP in awake state was regared as baseline, the increases in SBP pre-apnea and post-apnea and the increases in DBP post-apnea were significantly higher in REM sleep(-1.9 +/- 11.9 mm Hg, 32.6 +/- 20.6 mm Hg, 18.2 +/- 11.6 mm Hg, respectively) than in NREM sleep (-8.4 +/- 8.0 mm Hg, 20.4 +/- 6.9 mm Hg, 13.2 +/- 5.8 mm Hg, P < 0.05, respectively). (2) In different sleep stages, HR was markedly higher at the end of apnea than before apnea(NREM: 76 +/- 8 bpm vs 70 +/- 8 bpm, P < 0.05; REM: 85 +/- 11 bpm vs 71 +/- 8 bpm, P < 0.01). HR in post-apnea (P < 0.01) and the increase in HR during apnea (NREM: 6.9 +/- 2.2 bpm, REM: 14.1 +/- 10.1 bpm, P < 0.05) were remarkably higher in REM sleep than in NREM sleep, but not for pre-apneic HR. (3) In NREM sleep, HR in pre-apnea was significantly correlated with the increase in SBP and DBP during apnea(r = -0.699, P < 0.01; r = -0.602, P < 0.05, respectively); The increase in SBP during apnea in NREM sleep was also correlated with post-apnea HR (r = -0.669, P < 0.01). CONCLUSION: Sleep stage has effects on BP and HR and the changes in BP are correlated with the changes in HR during apnea in patients with OSAS.

Adult↗
PubMed2003

Sleeping energy expenditure in paediatric patients with obstructive sleep apnoea syndrome.

OBJECTIVE: To investigate sleeping energy expenditure in paediatric patients with obstructive sleep apnoea syndrome. DESIGN: Retrospective study. Setting. University teaching hospital, Hong Kong. PATIENTS AND METHODS: A retrospective analysis comparing sleeping energy expenditure in patients with confirmed obstructive sleep apnoea syndrome and control subjects matched for age, sex, and ideal weight for body height. Subjects were recruited from the Paediatric Chest Clinic and all had undergone overnight polysomnography and sleeping energy expenditure measurement by open-circuit indirect calorimetry using a metabolic cart and canopy system. The measurements were taken during slow-wave sleep. RESULTS: Twenty-four cases with obstructive sleep apnoea syndrome (apnoea hypopnoea index >5) and 23 control subjects were studied. Mean age and ideal weight for body height were 9.4 (standard deviation, 3.9) years and 152.5% (27.2%), respectively. Mean sleeping energy expenditure corrected for body weight for the cases and the control group were 44.83 (standard deviation, 10.49) Kcal/day and 40.71 (10.60) Kcal/day, respectively. Sleeping energy expenditure was not found to be associated with the severity of obstructive sleep apnoea syndrome (r=0.34, P=0.27). CONCLUSION: A trend towards greater sleeping energy expenditure was found in patients with obstructive sleep apnoea syndrome. Further studies on the metabolic aspects of this condition are required.

Calorimetry, Indirect↗
PubMedDate not supplied

Arousals and aircraft noise - environmental disorders of sleep and health in terms of sleep medicine.

World wide rules for sleep staging originate to 1967. Since then many investigations aimed to give numbers for the degree of sleep disturbances due to air traffic noise. But the variables used, such as the amount of relative sleep stages, total sleep time, or sleep efficiency, could not explain impairment in health and performance sufficiently. The beginning of the eighties has given new insight into the restorative functions of sleep, according to sleep fragmentation by micro-arousals. These are originating in autonomous dysfunctions during sleep, leading to non-restorative sleep. Environmentally related sleep disturbances are described, EEG and vegetative (micro)-arousals, and the actual knowledge in sleep medicine is given in terms of the international classification of sleep disorders (ICSD). The effects on health, and disturbed performance capacity during the day are shown by self ratings of 160 patients. Elevated metabolic rate caused by micro-arousal and/or insomnia, may play an additional role in health impairment.

Aircraft↗
PubMed1991

Sleep-waking cycle disturbance in patients with obstructive sleep apnea syndrome.

Eighteen (18) obese patients with clinically confirmed obstructive sleep apnea syndrome (OSAS) and five (5) obese persons with no apnea crises noticed during sleep apart from occassional loud snoring, have been polysomnographically assessed. The obtained results show that the patients with apnea syndrome sleep very badly, and consequently, shortened sleep latency and frequent body movements, along with apneas, are regarded as the leading polysomnographic symptoms. Vigilance profile during sleep, that is, interchange and frequency of each of sleep stages (I, II, III, IV, REM) are similar in both tested groups. The suppression of restitutive stages of sleep (III, IV, REM) is considered to be a dominant characteristic of vigilance during sleep in obese persons and obese persons with manifest apnea syndrome. Relatively prolonged sleep latency in obese persons without manifest apnea syndrome indicates, however, restitutively higher quality of their nocturnal sleep. Contrary to the patients with apnea syndrome, they do not suffer from excessive evening somnolence, so that their daily alertness and sleep vigilance during night are of a better quality, although the lack of deep and REM sleep is observed in them as well.

Adult↗
PubMed1991

The relationship between critical care nurses' knowledge about sleep, and the initiation of sleep promoting nursing interventions.

This descriptive correlation study examined the relationship between critical care nurses' sleep-promoting nursing interventions and their knowledge about sleep; the priority they gave to sleep; their perceptions about the ICU environment; the quantity and quality of sleep they perceived the patients to have obtained; and their sleep promoting nursing interventions. The data were described and then analysed using multiple regression/correlational analysis. Critical care nurses were not very knowledgeable about sleep. They perceived the ICU environment to be moderately conducive to sleep and perceived that they had only some ability to change the ICU environment in order to promote sleep. There was no statistically significant relationship between critical care nurses', sleep promoting nursing interventions and their knowledge about sleep. Several explanations for this are given. There was a statistically significant relationship between sleep promoting nursing interventions and the priority critical care nurses gave to sleep. Several implications for nursing research were drawn from the data and presented.

Critical Care↗
PubMed1994

[Prevention and treatment of sleep disorders through regulation] of sleeping habits].

Healthy sleeping habits is a complex balance between behaviour, environment and circadian rhythm. The quality of sleep can be improved by behaviour, e.g. eating tryptophan and carbohydrate rich foods, physical exercise in the afternoon or a cold shower just before going to bed. Total sleep time is maximal in thermoneutrality and decreases above and below the thermoneutrality zone. Thermoneutrality is reached for an environmental temperature of 30-32 degrees C without night clothing or of 16-19 degrees with a pyjama and at least one sheet. Noise also modifies sleep structure and above 50dB shortens total sleeping time. Although subjects do become subjectively accustomed to noise, vegetative cardiovascular reactivity to environmental noise remains unchanged. The spontaneous circadian awake/sleep cycle is 25 hours, slightly longer than the body temperature cycle, but when subjects are exposed to environmental synchronization, the two cycles coincide. In individuals undergoing temporal isolation, the two rhythms become independent often leading to subjective discomfort and fatigue. Certain factors including age can favour internal desynchronization. Other factors may include social contact, stress due to mental work load, and constant lighting which could lengthen the awake/sleep cycle. Caffeine blocks the receptors of adenosine, and thus its effects of inhibiting neurotransmission. Intake 30 to 60 minutes before sleeping shortens total sleep time and increases the duration of stage 2 and shortens stage 3 and 4. Alcohol may act as a relaxing, sedative agent when consumed just before sleeping but can also lead to night-time awakening due to sympathetic activation which does not return to baseline levels until the blood alcohol levels have returned to 0. Nicotine has a biphasic effect on sleep: at low concentrations, it leads to relaxation and sedation and at high concentrations inhibits sleep. A careful study of sleeping habits is the first step in evaluating complains of insomnia or hypersomnia. Before relying on drugs, treatment should start with attention to the sleep environment and personal habits.

Caffeine↗
PubMedDate not supplied

Effect of 64 hours of sleep deprivation upon sleep in geriatric normals and insomniacs.

Fifty-eight geriatric normal and chronic insomniac sleepers were screened with sleep recordings to define groups of 12 Normal (Sleep Efficiency greater than 85%) and Insomniac (Sleep Efficiency less than 80%) sleepers. All subjects then had 4 baseline sleep nights, 64 hours of total sleep loss, and 4 recovery nights. Insomniacs, had lower sleep efficiencies and less REM than Normals during baseline. Sleep efficiency was high (97%) in both groups on the first recovery night but decreased toward baseline values in both groups between the second (Normal) and fourth (Insomniac) recovery night. The groups had relatively little slow wave sleep, but had a significant increase on the first recovery night. Five Normals and one Insomniac had REM latency of less than 15 min on their first recovery night. This REM latency was found to be significantly correlated with the amount of slow wave sleep on baseline. Decreased REM latency in initial recovery sleep was interpreted as evidence of decreased pressure for slow wave sleep in aging.

Aged↗
PubMed1998

[Severity of obstructive sleep apnea syndrome relates to sleep architecture changes].

OBJECTIVE: To explore how obstructive sleep apnea syndrome (OSAS) affects sleep architecture and if OSAS severity and treatment relate to it. METHOD: A computer-assistant diagnostic system was used for polysomnography(PSG) recording. Respiratory events were scored automatically and corrected manually. Sleep was scored manually according to the standard set by Rechtschaffen. 31 controls and 147 OSAS patients(RDI > or = 5) were defined by PSG. 11 OSAS patients(RDI = 62.5 +/- 20.8) accepted nCPAP therapy. PSG were recorded both before and during nCPAP treatment. RESULT: (1) Compared with controls, OSAS group had increased sleep shift number (120 +/- 71 vs 92 +/- 60, P = 0.0106); (2) The number of slow wave sleep(SWS) (5 +/- 9 vs 8 +/- 8, P = 0.0035) and the ratio of total SWS time over total sleep time(TST) (5% +/- 8% vs 8% +/- 9%, P = 0.0062), were decreased and the rate of SWS deprivation(48% vs 26%, P < 0.05) were increased greatly in OSAS patients; (3) REM were less affected by OSAS than SWS because the ratio of its total time over TST, its onset number and deprivation rate had no significant difference between the two groups; (4) OSAS group had increased number of WASO (wake after sleep onset) (27 +/- 28 vs 19 +/- 18, P = 0.017) but the ratio of total WASO time over total sleep period had no significant difference between the two groups; (5) The ratio of total RWS(rapid wave sleep) time over TST (94 +/- 10 in OSAS group vs 91 +/- 12, P = 0.0136) and total RWS number(88 +/- 54 in OSAS group vs 65 +/- 45, P = 0.0075) were increased in OSAS group; (6) The above parameters were obviously disturbed in OSAS patients with RDI > or = 25 but had almost no change in patients with RDI < 25 compared with controls. (7) nCPAP could improve the above parameters but only number of WASO(no therapy: 34 +/- 20 vs therapy: 23 +/- 22, P = 0.011), shift number (no therapy: 151 +/- 62 vs therapy: 97 +/- 50, P = 0.019) and the ratio of total RWS time over TST (no therapy: 115 +/- 58 vs therapy: 69 +/- 34, P = 0.025) had statistical significance. CONCLUSION: OSAS severity relates to sleep architecture changes. Those had RDI < 25 had no change compared with control group. Sleep architecture changes could be improved by effective nCPAP therapy.

Adult↗