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Sleep onset and first cycle of sleep in human subjects: change with time of day.

The first cycle of sleep was studied in different situations: normal night sleep, naps, diurnal sleep after night shifts (3 x 8 shift workers). Results show two types of first cycle: some started with SWS (normal cycles), others with REM (sleep onset REM periods: SOREMPs). (1) Normal cycles: the length of SWS in the first cycle was positively correlated with prior wakefulness; conversely, the latency of SWS decreased as prior wakefulness increased; the decrease was due to the decrease in the length of the previous stage II or of the sleep onset latency (SOL). Length of sleep onset (SO) showed only few variations. The structure of the first cycle of shift workers' sleep probably reflects an important sleep loss. (2) SOREMPs occcurred during diurnal sleep. Some hypotheses about these cycles are discussed including REM 'pressures' (circadian, sleep loss) and inter-individual variations.

Adult

Sleep apnoea syndrome: states of sleep and autonomic dysfunction.

Eleven patients with upper airway apnoea during sleep (one with SHY-Drager syndrome) were monitored polygraphically for wakefulness, sleep, and cardiovascular variables. Systemic hypertension and most of the severe arrhythmias recorded during sleep were secondary to repetitive obstructive apnonea and were mediated through the autonomic nervous system. Sleep related elevations of pulmonary arterial pressure were not influenced by atropine or impaired autonomic functions. Upper airway sleep apnoea is sleep related; the type of sleep (REM or NREM) is critical in the appearance of abnormalities. The distinction between two patient subgroups (total sleep dependent and NREM sleep dependent) has haemodynamic, and possibly long-term, implications. Sleep apnoea syndrome should be looked for in pateints with the Shy-Drager syndrome.

Adult

Sleep electroencephalograms and sleep stages in hypoparathyroidism.

2 patients with hypoparathyroidism, one idiopathic and the other pseudoform, were studied by overnight polygraphic recording of the sleep EEG and related activities before and after start of treatment to investigate their sleep EEG patterns and states, with the results as follows. (1) Conspicuous abnormalities were noted in the sleep record, namely, disappearance of humps, spindles and hill waves, emergence of the mitten pattern and rather monotonous delta rhythm bursts. The EEGs, both awake and asleep, showed findings suggestive of a possible disorder of the desynchronizing mechanism of the brain stem. Normal sleep EEG patterns were restored after the serum calcium level had returned to the normal range. (2) In the course of overnight sleep, disturbance in the cyclic changes of sleep EEG pattern and absence of REM sleep were observed. Restoration to the normal course of sleep was achieved following the normalization of serum calcium level. Divalent calcium ion is considered to have intimate bearing upon the mechanism whereby synaptic chemical transmitters are activated. When viewed with reference to the monoamine hypothesis of Jouvet, the disturbance in the course of sleep observed in the present cases, especially the absence of or disturbed REM sleep, is inferred to be related to the hypocalcemia.

Child

Relationship of arousal threshold to sleep stage distribution and subjective estimates of depth and quality of sleep.

The relationship of arousal threshold, amounts of various sleep stages, and subjective rating of sleep was studied in two separate experiments involving 7 and 26 young adult subjects, respectively. Electroencephalographic sleep stage data, subjective response data, and arousal threshold data were collected over a series of nights in the sleep laboratory. Only nonsignificant relationships were found between magnitude of arousal threshold and amounts of various sleep stages or subjective rating of sleep quality in between-subjects analyses. However, when the nights representing extremes in arousal threshold were examined within-subject, it was found that nights of high threshold were accompanied by subjective reports of significantly better sleep in both studies and by a significant decrease in the amount of stage W in one study. Arousal threshold was not related to subjective depth of sleep in either study. Rather, subjective ratings of depth of sleep were significantly related to the amount of EEG-defined wakefulness and stage 1.

Adolescent

Recovery sleep following different visual conditions during total sleep deprivation in man.

The findings of visual impairment during total sleep deprivation were used as a basis for a possible link between vision and sleep. It was proposed that the level of visual load imposed during sleep deprivation was an important variable, and would have a substantial effect upon recovery sleep. Six young male subjects underwent two conditions of 64 h of sleep deprivation on separate occasions. One condition incorporated a high visual load, and the other a low load. Exercise and sound were balanced. All night sleep EEGs were taken for two baseline nights, and also for two recovery nights following each condition. There was a significant increase of stage 4 on all recovery nights and a REM rebound on the second recovery night. SWS, particularly stage 4, TST and REM density, were significantly greater following the high load. Implications of these findings for sleep theories and for sleep deprivation research are discussed.

Adult

Short and long sleep and sleeping pills. Is increased mortality associated?

Prospective epidemiologic data of the American Cancer Society disclosed that reported usual sleep durations among groups who complained of insomnia and sleeping pill use "often" overlapped with those of groups who had no complaints. Reports of insomnia were not consistently associated with increased mortality when several factors were controlled; however, men who reported usually sleeping less than four hours were 2.80 times as likely to have died within six years as men who reported 7.0 to 7.9 hours of sleep. The ratio for women was 1.48. Men and women who reported sleeping ten hours or more had about 1.8 times the mortality of those who reported 7.0 to 7.9 hours of sleep. Those who reported using sleeping pills "often" had 1.5 times the mortality of those who "never" used sleeping pills. These results do not prove that mortality could be reduced by altering sleep durations or by reducing hypnotic prescribing. Rather, studies are needed to determine the causes of these mortality risk factors.

Adult

Effects of a programmed reflexology therapy on sleep quality, insomnia, and fatigue among individuals with poor sleep quality: evidence for autonomic nervous system modulation.

Poor sleep quality is closely associated with autonomic dysregulation and increased risks of cardiovascular, metabolic, and mental disorders. Foot reflexology is a widely used complementary therapy; however, its physiological mechanisms and comparative efficacy remain insufficiently explored. This study aimed to compare the effects of manual reflexology treatment (MRT) and foot massage equipment (FEM) on autonomic nervous system function, sleep quality, insomnia severity, and fatigue in adults with poor sleep quality. Using a randomized crossover design, 32 participants with poor sleep quality received MRT and FEM interventions for 6 weeks each (once weekly, 30-40 min/session). Heart rate (HR), blood pressure, and heart rate variability (HRV; time- and frequency-domain indices) were assessed at weeks 1 and 6 before and after each intervention. Subjective outcomes included the Pittsburgh Sleep Quality Index (PSQI), Insomnia Severity Index (ISI), and Fatigue Assessment Scale (FAS). Following MRT, participants demonstrated significantly greater reductions in global PSQI scores and all PSQI components compared with FEM. MRT also resulted in larger improvements in insomnia severity and both mental and physical fatigue. In contrast, FEM primarily improved physical fatigue. Physiologically, MRT induced an immediate decrease in HR and significant increases in HRV time-domain indices (SDNN, RMSSD, pNN50), which were sustained after 6 weeks. Frequency-domain analysis further revealed reduced LF, increased HF, and a lower LF/HF ratio, indicating enhanced parasympathetic activity and cumulative autonomic modulation. In conclusion, programmed manual reflexology, delivered according to the TIDieR framework, is more effective than mechanical foot massage in improving autonomic balance, sleep quality, insomnia severity, and fatigue in individuals with poor sleep quality. These findings support MRT as a feasible and evidence-based non-pharmacological complementary intervention for sleep health promotion. TRIAL REGISTRATION: clinicaltrials.gov; NCT Number: NCT07402460; Registered 3 February 2026.

Adult

Plasma growth hormone and slow wave sleep increase after interruption of sleep.

A comparison was made of plasma hGH and of sleep stages during one night of undistrubed sleep and one night in which sleep was interupted by an hour of enforced wakefulness folowing the end of the second NREM-REM sleep cycle in 8 normal subjects. Plasma was sampled at 15-min intervals. HGH and slow wave sleep were both significantly increased in the two cycles immediately following the period awake compared with the same two cycles during nights of uninterruped sleep. The difference arose predominantly in the fourth cycle of the night, i.e., in the second cycle after the sleep interuption. The findings are consistent with the belief that extra wakefulness brings additional sleep of high RESTORATIVE properties.

Adult

[Effect of prolonged unidirectional migration of the sleep--wakefulness rhythm phase on human physiological functions, mental productivity and sleep].

The paper gives the results of three 30-day experiments carried out to study the effect of migration of the sleep--alertness cycle on physiological functions, psychic productivity and sleep of man. The migration was agravated by the initial change of the cycle which varied from +/- 7 to +/- 11 hours. All test subjects showed a counter-clockwise migration which amounted to a 1.5 hour shift every 4-5 days. All test subjects demonstrated functional cerebral changes, decline of psychic productivity and sleep disorders. The level of those disturbances depended on the value of the initial shift of the sleep--alertness cycle and on the cumulation of the migration effect. Those disorders were noted even when the prechanged sleep--alertness cycle approximated the normal pattern as a result of migration. The results indicate that the migrating day--night pattern, particularly in combination with the initial shift of the sleep--alertness cycle, cannot be recommended for manned space missions. Good health condition and high work capacity of cosmonauts can be maintained, only if a 24-hour sleep--alertness cycle with a normal sleep pattern is provided.

Adult

Peculiarities of human sleep in the case of double alternation of "sleep-waking" cycles.

The dynamics of sleep was studied in seven healthy subjects in two schedules, differing in the magnitude of the sleep intervals and their distribution over the 24 hour period. The first series provided for the use of two four-hour sleep intervals, the second six- and two-hour intervals. The investigations showed that the transition to a new schedule was accompanied by substantial qualitative and quantitative sleep disturbances, followed by a restoration of sleep as the subjects adapted. Less pronounced sleep disorders and more rapid restoration were observed in the schedule with nonuniform distribution of the intervals; more pronounced sleep disorders and a slowed restoration of sleep were observed on the schedule with two four-hour intervals.

Adult

Influence of diffuse brain stimulation (DBS) on human sleep. I. Sleep pattern changes.

A 20 min period of diffuse brain stimulation (DBS), administered just before sleep onset in 16 human subjects, appeared to alter significantly the first sleep cycle of the succeeding sleep. The length of the first sleep cycle and the amount of REM sleep increased, whereas a shift from deep to more superficial NREM sleep occurred. This effect of DBS on sleep is discussed with respect to data from the literature on the effect of narcotic DBS and on that of local brain stimulation in animals.

Adult

The pathophysiology of sleep disorders in pediatrics. Part I. Sleep in infancy.

In this part of the chapter we have described the characteristics of two alternating sleep states - REM and NREM sleep in preterm and full-term infants. We have indicated how individual physiologic measures, recorded during sleep, mature and become synchromized into patterns that define the sleep states. We have described abnormalities in this process and have related them to clinical populations of deviant infants. Throughout, we have emphasized the complexity of the process and the methodologic sophistication required to investigate adequately the multiple dimensions of sleep. Despite somewhat discrepant and confusing reports in the literature, we continue to believe that sleep studies will provide rewarding insights into the central nervous system functioning of the developing young infant.

Apnea

The pathophysiology of sleep disorders in pediatrics. Part II. Sleep disorders in children.

In this part of the chapter we have used new terminology and developed a new system for classification of sleep disorders in children. We suggest that excessive daytime sleepiness should be investigated by clinicians before troubles at school necessitate referral. The narcolepsy-hypersomnia syndrome generally has not been recognized in the pediatric age group. Symptoms of excessive fear of falling asleep need to be viewed in this context. Sleep apnea-hypersomnia has received insufficient attention in the American literature. It is a syndrome that affects both adults and children with potentially disastrous cardiovascular and pulmonary complications. The relationship of the sleep apnea-hypersomnia syndrome to the sudded infant death syndrome remains speculative, although preliminary results from our longitudinal study have indicated a possible link. Both the narcolepsy-hypersomnia and the sleep apnea-hypersomnia syndromes are reviewed in detail. In contrast, we review briefly the NREM dyssomnias, including night terrors, sleepwalking, sleep talking and enuresis. All are well known to clinicians dealing with children, and we have related them to findings emanating from the sleep laboratory. We suggest that they are physiologically rather than psychogenically based and frequently represent immaturities of the central nervous system. Finally, the insomnias of childhood are presented. We emphasize that they are rare, and after ruling out organic conditions and drug-dependency syndromes, cultural styles or family stresses generally account for the majority of complaints.

Apnea

The diagnostic value of the short sleep EEG and other provocative methods following sleep deprivation.

One hundred and eighty-five EEGs recorded after deprivation of sleep for 24 h were evaluated. Valuable diagnostic information was found in 59% of the EEG recordings; 24% of the EEGs contained seizure activity. The duration of the stages of sleep and the frequency of seizure activity, paroxysmal sharp wave groups and localizing findings were analyzed. The sleep stages A to C (based on the Loomis scale) were reached for about equal duration by an EEG recording of 30--40 min; sleep stage D was reached only shortly and stage E was not observed. Pathological EEG findings appeared for the most part in the sleep stages A and B. Localized findings were pronounced in stage C. No significant differences pertaining to the occurrence and form of EEG patterns were found between patient groups with primary generalized seizures, psychomotor seizures or those with unclarified disturbances of consciousness. The combination of the short sleep EEG following 24 h of sleep deprivation with subsequent use of the additional provocative methods of hyperventilation, photostimulation and hydration, yielded, in all, new information in 50% of the patients. Each of these additional methods contributed nearly equally to this information.

Adult

Neurohumoral correlates of sleep: further biochemical and physiological characterization of sleep perfusates.

Twenty cats were prepared surgically with electrodes for recording the EEG, Eye Movements and EMG and a push-pull cannula system in the midbrain reticular formation (MRF) allowing the extraction of perfusates during wakefulness or REM sleep. Proteins in the perfusates were analyzed by Isoelectric Focusing (IEF) polyacrylamide gels and Sodium Dodesyl Sulphate (SDS) slab gels. In addition analysis of glycoproteins was done by gas chromatography. In some cats the contribution of cerebrospinal fluid (CSF) proteins to perfusate proteins from brain tissue was studied by intraventricular injections of labelled leucine. The effect of sleep alterations on the protein cycle during sleep and wakefulness was also studied. The results of these experiments showed that most of the proteins in the perfusates are acidic, and that REM sleep perfusates contain 2 proteins M.W. 73.000 and 45.000 not present in awake perfusates, CSF or serum. It was also shown that CSF proteins do not appear to contribute to the proteins in perfusates, and that altering the sleep wake cycle, induces changes in the rhythm of protein release in perfusates. It is suggested that some relatively large polypeptides may participate in the regulation of REM sleep.

Animals

Effects of rapidly rotating shifts on sleep patterns and sleep structure.

Six young adult males were assigned to a rapidly rotating shift work schedule (2 d 6 am-4 pm, 2 d 4 pm-10 pm, and 2 d 10 pm-6 am). They lived in the laboratory and completed two rotations. Their nonshift activities were ad libitum including sleep times. The patterns and structure of sleep were analyzed. Shift times systematically affected sleep patterns. Within shifts, Ss slept as late as possible prior to the morning shift, went to bed shortly after the night shift, and slept approximately midway between shifts on the afternoon shift. In transitioning to a new shift, the new shift time tended to determine sleep time. Sleep was significantly longer in transitions between shifts. Sleep structure was not markedly changed.

Adolescent

Sleep and activity rhythms in mice: a description of circadian patterns and unexpected disruptions in sleep.

Studies on daily and circadian rhythms in wheel running and electrographically defined wakefulness, NREM sleep, and REM sleep in M. musculus were done to gather data on the temporal distribution of activity and sleep. Generally, peaks in NREM and sleep tended to coincide and to alternate with the coincident peaks of wakefulness and wheel running. However, during the active phase of the circadian wheel running cycle some NREM and REM sleep did occur; conversely, during its rest phase, wakefulness was often present. The most striking finding was that in mice with clearly entrained or free-running activity onsets, the circadian peak-through patterns in wakefulness, NREM, and REM sleep were not always distinct--they could be damped and/or polyphasic. Several explanations of these phenomena are considered.

Animals