Sleep Following Sustained Exercise

This study was designed to assess the effect of individually calibrated sustained, static exercise on sleep. Normal subjects engaged in 80 min of static muscular activity at 40% of maximal levels. The exercise ended 2 hrs before bedtime. Standard polysomnographic measures were recorded during sleep. The time to sleep onset was significantly reduced relative to nonexercise nights. Other significant comparisons (increased slow-wave sleep and decreased movement time after exercise) were confined to the period preceding the first REM episode. The results indicated that the type of exercise may be related to the effect on sleep latency. The data supported a restorative theory of slow-wave sleep.     

Exercise and Sleep Loss: Effects on Recovery Sleep

The effects of exercise and sleep loss on recovery sleep were studied in young male naval volunteers. For 1 hr out of every 4 hrs during a 40-hr period, 20 subjects rested in bed and 10 subjects bicycled. Eleven measures of recovery night sleep were selected for comparison of the bedrest and exercise groups. Only one reached significance under the conservative Dunn-Bonferroni criterion: the exercise group had a higher percent total sleep time. The results indicate that exercise does increase the effects of sleep loss on recovery sleep, but that there is no simple, direct effect on specific sleep stages.     

Physical Fitness, Exercise, and REM Sleep Cycle Length

It has been suggested, on the basis of phylogenetic and ontogenetic data, that the length of the REM sleep cycle is negatively related to metabolic rate. However, experimental studies have not consistently found this relationship. We report the effects of two variables, the level of physical fitness and the amount of daytime exercise, on sleep cycle length. Since both physical fitness and exercise involve increased levels of energy expenditure, and thus increased metabolic rate, it was predicted that they would he negatively related to cycle length. The sleep of 46 subjects (20 fit and 26 unfit) was assessed on nights following both exercise and non-exercise conditions. The cycle length of fit subjects was found to be shorter than that of unfit subjects. However cycle length on a night following daytime exercise did not differ from that on a night following a no-exercise day. We conclude that sleep cycle length is responsive to relatively long term variations in energy expenditure, but not day to day changes.     

Sleepiness and REM Sleep Recurrence: The Effects of Stage 2 and REM Sleep Awakenings

Determinants of daytime sleepiness include sleep length, sleep continuity, and circadian factors. Sleep stage composition has not been seen as influencing subsequent daytime functioning; however, earlier studies did not focus explicitly on sleepiness. The present experiment studied the effects of selective sleep-stage restriction on an objective measure of sleep tendency, and explored the relationship between sleepiness and subsequent REM recurrence during REM deprivation. Daytime sleep latency was measured by a modified Multiple Sleep Latency Test prior to and following two nights of awakenings from either REM or Stage 2 sleep in 16 normal young adults. Sleep latency following these awakenings was also measured. REM sleep and Stage 2 awakenings produced comparable levels of sleepiness, both during the Awakening Nights and subsequent daytime Multiple Sleep Latency Testing. Pooling the groups, daytime and nocturnal sleepiness measures were correlated within individuals. In the REM-Awakening Group, Pre-Awakening daytime sleepiness was associated with the tendency for REM sleep to recur following experimental awakenings. Comparable levels of sleepiness may result from nonspecific processes such as sleep curtailment and fragmentation, or alternatively from separate REM and Stage 2 mechanisms. The relationship between REM sleep and sleepiness is discussed in the context of both state and trait models.     

REM Sleep Interruption: Experimental Shortening of REM Period Duration

This experiment concerns itself with the extent to which psychological factors can influence normal sleep patterns. After 4 baseline nights of uninterrupted sleep, each of 4 Ss was awakened in the course of 2 nights during every REM period about 10 min following each REM onset. Ss, however, were not REM deprived. The interruption nights were followed by a recovery night of uninterrupted sleep. All nights were consecutive. The results show that during recovery nights all Ss continued to have significantly shorter than normal REM periods by going into NREM sleep at about the time they would have been awakened during the interruption nights. These shortened REM periods occurred even during early morning hours, when REM periods normally become longer. Arguments are advanced that this finding may best be explained in terms of a conditioned avoidance response.     

Congenital Nystagmus and Sleep: A Replication

In 8 subjects with congenital nystagmus, clearly manifested nystagmus was present while awake, with eyes open and closed, and during a variety of experimental tests, but could not be definitely discerned during REM and NREM sleep stages. However, conjugate REMs were present during the REMPs of all 8 subjects and could not be distinguished from patterns recognized in normal subjects. Brief episodes of reduced amplitude series of jerks were occasionally observed which could be considered to be “depressed” nystagmus, but such phenomena have been observed in the records of normal subjects. This replicates the findings of our previous report.     

The Effects on Subsequent Sleep of an Acute Restriction of Sleep Length

This experiment was designed to test the effects on subsequent sleep of a restriction in sleep length on the previous night. Eight male subjects were studied. After baseline recordings were made, sleep was restricted to either a period between 4-8 am or to a period between 6–8 am. On the night following the restriction of sleep the subjects retired at 11 pm and they were permitted to sleep ad lib in the morning. The restricted sleep periods resulted in differential sleep deprivation. Stages REM and 2 were markedly reduced whereas stages 3 and 4 showed little or no reduction in amount. There were significant reductions in sleep latencies and in the amount of lime spent in stages 0 and 1. The first 8 hrs of ad lib sleep following the 2 restricted sleep periods did not differ in any significant way from the 8 hrs of baseline sleep. When sleep was permitted to continue until the subjects awakened spontaneously, the sleep after the restriction of sleep to‘i hrs was significantly longer and displayed significantly more of stages REM and 2 when compared with the baseline ad lib sleep condition. The ad lib sleep period following the 4 hr condition showed similar changes although the differences were not statistically significant. The significant reductions in stages KEM and 2 during the restricted sleep periods were attributed to the effects of reduced steep length per se. The increases in sleep length and specifically the increases in stages REM and 2 during the ad lib sleep periods were attributed to a differential sleep “debt” accruing from restricted sleep length.     

Effects of Prolonged Sleep Deprivation, With and Without Chronic Physical Exercise, on Mood and Performance

The effects of physical exercise and sleep deprivation on mood and cognitive performance were studied in 12 healthy young male volunteers deprived of sleep on two occasions. During the first 60-hr period without sleep, half of the subjects walked on a treadmill at 25–30% of their maximum aerobic capacity (Exercise condition) for 1 out of every 3 hrs while the remaining 6 subjects remained physically inactive (No Exercise condition) during that same hour. Eight weeks later the same 12 subjects underwent an identical sleep-deprivation protocol except that those who were previously inactive exercised, while those who previously exercised remained inactive. Throughout the sleep deprivation periods, subjects in both conditions completed subjective assessments of fatigue, sleepiness and mood every 3 hrs, performed an auditory vigilance task every 6 hrs, and completed a cognitive test battery every 12 hrs. The results revealed clear decrements in mood and performance as a function of sleep loss. However, with the exception of somewhat more long reaction times in the Exercise condition, exercise neither increased nor decreased the impairment induced by sleep deprivation.     

Physical Fitness, Exercise, and Human Sleep

Restorative theories of SWS predict a positive relationship between SWS and daytime exercise. However the relevant data appear contradictory. It was hypothesized that the discrepancy in the literature was due to the varying physical fitness levels of subjects used in these studies. The hypothesis was tested, using human subjects, by varying amount of exercise and level of fitness in a 2x2 design. Two effects were observed, both supporting the hypothesis. First, fit subjects had higher levels of SWS than unfit subjects. Second, following exercise, the level of SWS increased in fit, but remained unchanged in unfit subjects.     

The Effects of Continuous, High Intensity, White Noise on the Human Sleep Cycle

Eight male college students slept for 8 consecutive nights under conditions of 93 ± 2 dB white noise (N) and under normal quiet conditions (Q). On N nights the percentage of total sleep time spent in stage REM was decreased (p < .001), the percentages of stages 1 and 2 were increased (p < .05, p < .001, respectively) and REM latency was increased (p < .02) compared to Q nights prior to N nights. On Q nights following N nights the percentages of stage REM increased above baseline levels indicating compensatory recovery effects from REM sleep deprivation on the prior N nights. Stages 3 and 4 remained unchanged throughout the study. The reduction in stage REM on N nights was directly attributed to the effects of noise on the CNS and not a secondary result of an increased number of awakenings on N nights.     

Heart Rhythm Control During Sleep in Ischemic Heart Disease

This paper deals with a computer-aided study of heart rate (HR) control during different sleep stages in 20 healthy volunteers and 75 ischemic heart disease (IHD) patients. In healthy subjects, the parasympathetic HR control was increased and the sympathetic control decreased during stages 1, 2, 3, and 4. REM sleep was characterized by a marked decrease in parasympathetic and a slight elevation in sympathetic contribution. Typical, “reduced” and “paradoxical” HP sleep patterns (HRSPs) were observed in IHD patients. The typical HRSP was similar to that observed in healthy subjects; the reduced HRSP was characterized by HR constancy, and the paradoxical HRSP by an HR increase in stages 3 and 4, and a decrease in REM sleep. The reduced HRSP was associated with the more frequent occurrence of cardiac abnormalities during REM sleep. HR oscillations during stage 2 depended on periodic apnoea episodes and were associated with cardiac abnormalities such as more frequent heart failure and cerebral blood flow disturbances, and overweight.     

心率变化特征与睡眠分期耦合关系研究

心率是非脑电方法判断睡眠分期的一个重要指标，提出了一种把睡眠分期进行定量化、模糊化描述的新思路，并详细给出了判断心率与睡眠分期耦合关系的新方法，这种方法具有简便、快速的特点。实验结果表明：健康人和SAHS病人的心率变化特征与睡眠时相均具有较好的相关性，其中健康人的相关性更高。     

The Time Course of the Probability of Transition Into and Out of REM Sleep

Study Objectives:

A model of rapid eye movement (REM) sleep expression is proposed that assumes underlying regulatory mechanisms operating as inhomogenous Poisson processes, the overt results of which are the transitions into and out of REM sleep.

Design:

Based on spontaneously occurring REM sleep episodes (“Episode”) and intervals without REM sleep (“Interval”), 3 variables are defined and evaluated over discrete 15-second epochs using a nonlinear logistic regression method: “Propensity” is the instantaneous rate of into-REM transition occurrence throughout an Interval, “Volatility” is the instantaneous rate of out-of-REM transition occurrence throughout an Episode, and “Opportunity” is the probability of being in non-REM (NREM) sleep at a given time throughout an Interval, a requisite for transition.

Setting:

12:12 light:dark cycle, isolated boxes.

Participants:

Sixteen male Sprague-Dawley rats

Interventions:

None. Spontaneous sleep cycles.

Measurements and Results:

The highest levels of volatility and propensity occur, respectively, at the very beginning of Episodes and Intervals. The new condition stabilizes rapidly, and variables reach nadirs at minute 1.25 and 2.50, respectively. Afterward, volatility increases markedly, reaching values close to the initial level. Propensity increases moderately, the increment being stronger through NREM sleep bouts occurring at the end of long Intervals. Short-term homeostasis is evidenced by longer REM sleep episodes lowering propensity in the following Interval.

Conclusions:

The stabilization after transitions into Episodes or Intervals and the destabilization after remaining for some time in either condition may be described as resulting from continuous processes building up during Episodes and Intervals. These processes underlie the overt occurrence of transitions.

Citation:

Bassi A; Vivaldi EA; Ocampo-Garcées A. The time course of the probability of transition into and out of REM sleep. SLEEP 2009;32(5):655-669     

Effect of Sleep Stage and Stimulus Intensity on Auditory Average Evoked Responses

Auditory average evoked responses (AERs) to clicks ranging from 50 to 80 dB were studied in 9 normal adults while awake and during sleep. AER amplitude tended to increase little from 50 to 80 dB in waking subjects but increased markedly in sleeping subjects during stages 3 and 4. Rapid eye movement (REM) and stage 1 sleep had small amplitude AER.S in comparison with other sleep stages, individuals who showed decreases in amplitude at high intensities while awake slept significantly longer during the experimental nights.     

Effect of Varying the Time of Sleep on Sleep, Vigilance, and Self-Rated Activation

The effect of varying the time of sleep (2100-0500, 2400-0800, and 0300-1100 hrs) on the sleep, vigilance, and self-rated activation of 9 normal subjects was assessed. REM% increased, and Stage 2% decreased, with progressively later bedtimes. An hour by hour analysis showed, however, that the increase in REM sleep was confined to the second 3 hrs of sleep. Vigilance and self-rated activation, assessed 30 min after waking, at midday and in the early evening, did not differ between conditions but varied reliably with time of day. It is concluded that shifts away from the conventional 2400-0800 sleep period do not impair performance. Rather, the changes in sleep (between conditions) and performance (within conditions) are, in the main, consistent with the known circadian rhythms of REM sleep propensity and performance efficiency.     

The Effects of a Restricted Sleep Regime on the Composition of Sleep and on Performance

This study examined the effects of restricting sleep to the first or second half of the night on the composition of sleep and on performance. Eight young women who regularly slept for 8–8.5 hrs a night had their sleep restricted to the first or second half of the night for two consecutive nights. Performance of a 20-min unprepared simple reaction time task was measured at fixed times of day for the two restricted sleep conditions and for a full night sleep control condition. Restricting sleep to the second half of the night produced higher amounts of REM sleep and Stage 4 sleep and lower amounts of Stage 2 sleep compared to restricting sleep to the first half of the night. Both restricted sleep conditions impaired performance relative to the full night sleep control, and performance was worse after two nights of restricted sleep than after one night of restricted sleep. The results show that the effects of a restricted sleep regime on the composition of sleep are partly a function of the time of night to which sleep is restricted. It is suggested that the performance deficits are due to loss of sleep per se rather than due to any change in the composition of sleep.     

Sleepiness and Sleep State on a 90-Min Schedule

The effects of REM and slow wave sleep (SWS) on subjective sleepiness were studied in 10 subjects placed on a 90-min sleep-wakefulness schedule for either 5^1/3 or 6 (24-hr) days. Subjects were permitted to sleep for 30-min periods separated by 60 min of enforced wakefulness. Sleep recordings showed that sleep onset REM periods occurred frequently; REM and SWS appeared during the same sleep period only 27 times; and REM sleep tended to occur on sleep periods that alternated with SWS periods. Sleepiness was measured using the Stanford Sleepiness Scale (SSS) given 15 min before (pre-sleep) and 15 min after (post-sleep) each sleep period. Average SSS ratings showed a 24-hr fluctuation in sleepiness. In addition, negative and positive SSS changes tended to alternate with each 90-min period. Significant correlations were found with post-sleep SSS ratings and SWS and with pre-sleep SSS ratings and REM sleep. Differences between pre- and post-sleep SSS scores were also correlated with the sleep states: increased sleepiness was correlated with SWS and decreased sleepiness with REM sleep.     

基于谱分析方法提取心动周期变异性中的睡眠结构信息

利用心动周期的谱分析方法 ,充分挖掘了心动周期变异性中与脑电睡眠分期信息相关的特征参数 ,并利用主成分分析法去除掉了特征之间的相关性 ,最后利用基于 Fisher分类准则的决策树分别建立了健康人和睡眠呼吸暂停低通气综合症病人的睡眠分期全自动识别模型。试验结果表明 ,该模型准确性好 ,鲁棒性强     

The Effects of Presleep Stimuli of Different Sources and Types on REM Sleep

The sleep patterns of 12 experienced meditators and 9 age-matched prospective meditators were compared to determine the effect of presleep stimuli of different sources and types on rapid eye movement (REM) sleep. All subjects were EEG monitored for two nights. On both nights the experienced meditators attended to internal stimuli, i.e. meditated prior to sleep, and the prospective meditators attended to external stimuli, i.e. listened to music through earphones, for an equal time. The music group had a significantly higher REM percent. Post hoc tests showed this was not due to a rebound following a difficult adaptation night. To test whether the elevation following music was a response specific to those committed to presleep external stimulus reduction, a second study compared the REM percent of a non-meditation oriented student sample following presleep verbal or music stimulation to their base rate. These subjects showed REM percents higher than their base after music and lower than base following verbal stimulation.     

Effects of Acute 3, 4-Methylenedioxymethamphetamine on Sleep and Daytime Sleepiness in MDMA Users: A Preliminary Study

Study Objective:

3, 4-Methylenedioxymethamphetamine (MDMA) affects monoamine neurotransmitters that play a critical role in sleep and daytime alertness. However, the acute effects of MDMA on sleep and daytime sleepiness have not been studied under placebo-controlled conditions. This study was designed to establish the effects of acute MDMA or placebo administration and sleep restriction on sleep and daytime sleepiness.

Design:

Participants with a history of MDMA use were studied on 3 sessions of 3 nights (baseline, treatment, and recovery) and 2 days (following night 2 and 3) per session. On treatment nights (night 2), participants received placebo or 2 mg/kg of MDMA or underwent a restricted bed schedule with placebo. Sleep restriction was a positive control to compare sleep loss and consequent sleepiness associated with MDMA use. The scheduled sleep period was 8 hours long on nonrestricted nights, and standard sleep recordings and daytime sleepiness tests were conducted. Age-matched controls received 1 night and day of standard sleep and daytime sleepiness testing.

Setting:

Sleep laboratory

Participants:

Seven recreational MDMA-users and 13 matched control subjects.

Measurements and Results:

Acute MDMA shortened sleep primarily by increasing sleep latency, and it reduced stage 3/4 sleep and suppressed rapid eye movement (REM) sleep. The MDMA-reduced sleep time was not associated with increased daytime sleepiness the following day, as was seen in the sleep-restriction condition. Compared with control subjects, the MDMA users on the first night in the laboratory had shorter total sleep times and less stage 3/4 sleep. Average daily sleep latency on daytime sleepiness tests the day after nighttime placebo administration was increased in MDMA users compared with the control subjects, and MDMA users had an elevated number of sleep-onset REM periods on these tests, compared with control subjects.

Conclusions:

Acute MDMA administration disrupts sleep and REM sleep, specifically, without producing daytime sleepiness such as sleep restriction does. Compared with control subjects, recreational MDMA users showed evidence of hyperarousal and impaired REM function. The mechanism behind these effects is likely due to the deleterious effects of MDMA on catecholamines.^1–3

Citation:

Randall S; Johanson CE; Tancer M; Roehrs T. Effects of acute 3, 4-methylenedioxymethamphetamine on sleep and daytime sleepiness in MDMA users: a preliminary study. SLEEP 2009;32(11):1513-1519.