Showing papers on "Slow-wave sleep published in 1981"

Activity of norepinephrine-containing locus coeruleus neurons in behaving rats anticipates fluctuations in the sleep-waking cycle

Abstract: Spontaneous discharge of norepinephrine-containing locus coeruleus (NE-LC) neurons was examined during the sleep-walking cycle (S-WC) in behaving rats. Single unit and multiple unit extracellular recordings yielded a consistent set of characteristic discharge properties. (1) Tonic discharge co-varied with stages of the S-WC, being highest during waking, lower during slow wave sleep, and virtually absent during paradoxical sleep. (2) Discharge anticipated S-WC stages as well as phasic cortical activity, such as spindles, during slow wave sleep. (3) Discharge decreased within active waking during grooming and sweet water consumption. (4) Bursts of impulses accompanied spontaneous or sensory-evoked interruptions of sleep, grooming, consumption, or other such ongoing behavior. (5) These characteristic discharge properties were topographically homogeneous for recordings throughout the NE-LC. (6) Phasic robust activity was synchronized markedly among neurons in multiple unit populations. (7) Field potentials occurred spontaneously in the NE-LC and were synchronized with bursts of unit activity from the same electrodes. (8) Field potentials became dissociated from unit activity during paradoxical sleep, exhibiting their highest rates in the virtual absence of impulses. These results are generally consistent with previous proposals that the NE-LC system is involved in regulating cortical and behavioral arousal. On the basis of the present data and those described in the following report (Aston-Jones, G., and F. E. Bloom (1981) J. Neurosci.1: 887-900), we conclude that these neurons may mediate a specific function within the general arousal framework. In brief, the NE-LC system may globally bias the responsiveness of target neurons and thereby influence overall behavioral orientation.

Cumulative Effects of Sleep Restriction on Daytime Sleepiness

Abstract: Sleep and daytime sleepiness were evaluated in 10 young adult subjects to determine whether restricting nocturnal step by a constant amount produces cumulative impairment. Subjects were studied for 12 consecutive days, including 3 baseline days with a 10-hr time in bed, 7 days with sleep restricted to 5 hrs, and 2 recovery days. In 5 subjects, recovery included a 10-hr time in bed; in the remaining subject, recovery induced a 5-hr time in bed with a 1-hr daytime nap. Sleepiness was measured using two self-rating scales and the multiple sleep latency test. During sleep restriction, nocturnal stage 2 and REM sleep were reduced and slow wave sleep was unaffected. Stanford Sleepiness Scales showed an immediate increase in daytime sleepiness that reached a plateau after 4 days. An analog sleepiness rating scale showed increased sleepiness after 2 restricted nights and leveled off after the fourth restricted night. The multiple sleep latency tests showed no effect of sleep restriction until the second day, followed by a progressive increase in sleepiness that persisted through the seventh sleep restriction day. During the recovery period, daytime sleepiness returned to basal values on all three measures following one full night of sleep; with a daytime nap, no further cumulative effects of sleep restriction were seen.

The circadian variation of experimentally displaced sleep.

Abstract: In a group of 6 male subjects sleep was displaced to seven different times of day (one displacement condition per week). The subjects were isolated from external time cues (daylight, clocks, noise) and sleep was allowed to terminate spontaneously. The results showed a pronounced time-of-day variation of total sleep time, stage 2, and rapid eye movement (REM) sleep. Maxima occurred after bedtimes at 1900 hr and 2300 hr, while the minima occurred after bedtimes at 0700 hr and 1100 hr. The latter also was the time of maximum propensity to wake up. Slow wave sleep showed a rapid decrease from high initial levels, irrespective of time of day. Ratings of sleepiness showed a highly significant circadian variation peaking between 0500 hr and 0700 hr. The lowest level of sleepiness coincided with the maximum tendency to wake up, and it was suggested that sleep termination may be closely related to the sleepiness/alertness rhythm.

Age-related changes in sleep in depressed and normal subjects

Abstract: All-night electroencephalographic (EEG) sleep data were examined as a function of age in normal control subjects and hospitalized, unmedicated depressed patients with primary affective illness. By analysis of variance, Total Sleep time, Delta Sleep, Sleep Efficiency, Rapid Eye Movement (REM) Sleep, and REM Latency decreased as a function of age, whereas Early Morning Awake time and Intermittent Awake time increase. Compared with normal controls, after the effects of age were covaried out, depressed patients had a greater Sleep Latency, Early Morning Awake time, Intermittent Awake time, Duration and REM Density of the first REM period, and average REM Density for the night, as well as less Sleep Efficiency, less Delta Sleep, and shorter REM Latency. Early Morning Awake time increased with age in depressive but not in normals.

Disturbed sleep and prolonged apnea during nasal obstruction in normal men

Abstract: Anecdotal observations suggested that poor quality of sleep is a frequent complaint during upper respiratory infections (URI). Nasal obstruction occurs frequently during URI and causes sleep apnea in some infants. Sleep apnea disrupts normal sleep and could explain the complaints of poor sleep quality during URI in adults. Accordingly, 10 normal men had full night recordings of sleep stages and breathing rhythm before and during nasal obstruction. The order of obstructed and nonobstructed nights was randomized after a standard acclimatization night. During nasal obstruction, time spent in the deep sleep stages decreased from 90 +/- 11.2 (SEM) to 71 +/- 12.9 min (p less than 0.05), whereas significantly more time was spent in Stage 1 sleep (p less than 0.03). This loss of deep sleep during obstruction was associated with a twofold increase in sleep arousals and awakening (p less than 0.01) resulting from an increased (p less than 0.02) number of apneas (34 +/-19 during control sleep versus 86 +/- 34 during obstructed sleep). Apneas of 20 to 39 s in duration became 2.5 times more frequent (p less than 0.05) during obstruction. Oxygen saturation was studied in the last 4 subjects using an ear oximeter. Desaturation (SaO2 less than 90%) occurred 27 times during control sleep compared with 255 times during obstructed sleep. These desaturation episodes occurred only during apneas. All men complained of poor sleep quality during nasal obstruction. We concluded that apneas, sleep arousals and awakenings, and loss of deep sleep occur during nasal obstruction and may explain complaints of poor sleep quality during URI.

Slow-wave sleep: a recovery period after exercise

Abstract: Sleep recordings were carried out on athletes on four successive nights after completing a 92-kilometer road race. Significant increases in total sleep time and slow-wave sleep were found after this metabolic stress. The results show a definite exercise effect on sleep and support sleep-restoration hypotheses.

Altered sleep physiology in chronic alcoholics: reversal with abstinence.

Abstract: Somnograms obtained from recently abstinent chronic alcoholics reveal gross disruption succinctly described as "fractured" sleep. Sleep onset is delayed and the rhythmic properties of the sleep pattern are markedly disturbed with numerous brief arousals and changes of sleep stage. Excessive stage 1 and stage rapid eye movement sleep are present while the high voltage slow wave sleep is markedly reduced or absent. With continued sobriety (9 mo or more) the sleep stage percentages tend to return to normal levels, but the disruption of the sleep pattern persists after as much as 21 mo of abstinence.

Serotoninergic mechanisms and sleep.

Abstract: Serotoninergic neurons play a critical role in the sleep mechanism. This is supported by a lot of converging experiments and has provided the basis for a great deal of research. A critical analysis is first developed, supported by more recent data which are not in complete agreement with the theory that raphe nuclei are actively implied in slow wave sleep. On the other hand, numerous experimental evidences were collected during the sixties on the EEG synchronizing influence of the lower brain stem and preoptic area. Recent data showed that serotonin could also play here a crucial role in the induction of sleep. Nevertheless, at the moment, it is difficult to make a critical examination of the interaction and regulation of these putative 5-HT-related areas of the brain, but we can postulate that the occurrence of true physiological sleep-waking continuum necessitates their successive or conjoint activation.

Persistence of the circadian rhythm of REM sleep: a variety of experimental manipulations of the sleep-wake cycle.

Abstract: Many studies of nocturnal sleep, daytime naps, and phase shifts of sleep time indicate that rapid eye movement (REM) sleep has a circadian rhythm with an acrophase in the early morning, whereas slow wave sleep (SWS) correlates positively with the length of prior wakefulness. We confirmed that REM sleep has a stable circadian variation; large REM sleep amounts occurred in morning naps despite increase of SWS, owing to 1 night of total sleep deprivation. Heart rate and oral temperature both continued to show a circadian rhythm in spite of 1 night of total sleep deprivation. The lowest point of both cycles occurred in the early morning and the highest point in the late afternoon. The amount of REM sleep was largest near the low point of the circadian cycle of oral temperature and heart rate, and smallest at the high point, indicating a phase reversal relationship between the circadian rhythm of REM sleep and the autonomic functions. During 1 week of absolute bed rest under entrained conditions, subjects were most able to sleep near the low point of their oral temperature cycle and least able to sleep near the high point, and the amount of REM sleep was largest near the low point of the oral temperature and smallest at the high point.

Behavioral and physiological correlates of brain serotoninergic unit activity.

Abstract: Raphe unit activity in rats and cats displays a slow and regular discharge pattern across a variety of situations. The activity is, however, state-dependent, displaying a marked reduction during slow wave sleep and almost complete quiescence during REM sleep. Other than the level of synaptic serotonin, very little is known about the physiological variables affecting these neurons. Behaviorally, raphe neuron activity is correlated with arousal or tonic motor activity, and appears to be driven by phasic afferent input. It is hypothesized that these neurons exert a general modulatory role upon physiology and behavior.

Twenty-Four-Hour Pattern of Growth Hormone Secretion in the Rhesus Monkey: Studies Including Alterations of the Sleep/Wake and Sleep Stage Cycles

Abstract: The 24-h pattern of GH secretion and its possible relation to the sleep/wake cycle and to sleep stages were studied in 12 male rhesus monkeys. Blood samples were drawn every 15 min for 96 h, 24 h, or shorter periods of time through chronic right atrial catheters which extended through the wall into the adjacent room. In addition, activity rating (daytime) and determination of sleep stages from electroencephalogram recordings (nighttime) were done. GH profiles were obtained during undisturbed conditions and during deprivation of nap, 5 h total sleep, slow wave sleep (SWS), and rapid eye movement (REM) sleep. GH secretion was episodic, with peak concentrations often exceeding 20 ngeq/ml and nadirs mostly below 1 ngeq/ml. Autocorrelation analysis demonstrated a circadian and an ultradian rhythm during undisturbed conditions. However, the cycle length of the ultradian rhythm showed large inter- and intraindividual variations (from 3--6 h). Neither cross-correlation analysis between hormonal and activity/electroencephalogram sleep stage time series nor results of deprivation experiments produced evidence for a link between nap phases, the sleep/wake cycle, or the SWS/REM sleep stage cycle on the one hand and the GH secretory pattern on the other hand. However, while SWS deprivation was highly effective, REM deprivation did not substantially reduce total REM sleep time due to frequent entries into abortive REM sleep epochs. During the daytime, there was no significant correlation between activity/arousal and GH, but during the night, there was a significant positive correlation between stage waking and GH. A direct or indirect synchronizing effect of the matutinal light change is suggested by the pattern of the 24-h curve of mean GH concentrations during undisturbed conditions: a steep increase from very low concentrations at light onset, followed by a succession of nadirs and peaks at approximately 4.5-h intervals. However, the nadirs became progressively more shallow until there was no apparent periodicity during the night due to the loss of synchronization. It is concluded that GH in the rhesus monkey shows a circadian and an ultradian periodicity. However, in contrast to man, sleep and SWS are not important determinators of the 24-h GH pattern.

Effect of continuous traffic noise on percentage of deep sleep, waking, and sleep latency

Abstract: When subjected to alternating quiet nights (32 dB) and noise nights (equivalent levels of 47 dB) a group of 14 subjects showed an average increase in the fraction of deep sleep of about 2.5% resulting from the traffic noise. Another group of 12 subjects whose noise nights were at 60 dB had an average of 4.6% increase in deep sleep during these nights. The number of wakings also increased for both groups but, as was found before, this adapted rapidly with the number of nights. The average latency of sleep onset does not appear to be affected by the traffice noise but individual differences are great and may be of opposite sign. Latency of sleep onset and waking both show appreciable ‘‘laboratory effect’’ which takes longer to disappear than the one or two nights usually assumed.

Thyrotropin-releasing hormone effects in the central nervous system: dependence on arousal state.

Abstract: Thyrotropin-releasing hormone was microinjected into the dorsal hippocampus of ground squirrels (Citellus lateralis) when they were at different levels of arousal, as assessed by electrophysiological and behavioral criteria. When administered to the awake animal, thyrotropin-releasing hormone produced dose-dependent decreases in body temperature accompanied by behavioral quieting and reductions in metabolic rate and electromyographic activity. The magnitude of these effects was greater when the peptide was microinjected during a period of behavioral activation. In contrast, administration of the peptide during slow wave sleep produced increased thermogenesis, an increase in electromyographic activity, and an increase in the amount of electroencephalographic desynchronization.

REM sleep, naps, and depression.

Abstract: Continued interest in rapid eye movement (REM) sleep abnormalities in depression stimulated comparative studies on daytime naps versus nighttime sleep. In a group of 15 depressed patients, REM latencies in morning and afternoon naps were similar to the shortened REM onset at night. Although REM latency did not vary across the three times, the propensity for REM sleep appeared to be greater in the morning nap than in the afternoon nap and the early portion of nocturnal sleep. Finally, the data suggest that responders to tricyclic treatment tend to be poor sleepers during daytime naps.

Generalized epilepsy with spike-wave paroxysms as an epileptic disorder of the function of sleep promotion.

Abstract: A new hypothesis is offered regarding the pathomechanism of generalized epilepsy with spike-wave paroxysms (GESw) based on the pertaining literature and personal investigations. The first section is devoted to a critical overview of the development of theories regarding GESw. The centrencephalic theory, the debate on subcortical versus cortical origin, the "corticoreticular" hypothesis of Gloor and, finally, the "dyshormic" concept of Niedermeyer are outlined. In the next section it is shown that there is a particular optimum zone between sleep and wakefulness and between REM and slow wave sleep which highly favours the occurrence of spike-wave paroxysms. According to our investigations into the dynamics within this critical zone, the spike-wave paroxysms always appear with characteristic fluctuations of the level of consciousness where the changes towards awakening are always followed by rebounds towards sleep. Hence, the dynamic properties of this unstable border zone become especially interesting in the genesis of spike-wave paroxysms. It has been shown that even without epilepsy, a dynamics can be observed in the micro-oscillations in the depth of sleep which could be interpreted according to the reciprocal induction regulation model. In our concept the process of falling asleep emerges from rebounds of the sleep promoting system in response to sensory inputs streaming in from the external environment. According to this model, arousal influences in sleep have a sleep promoting effect. We interpret in this way all synchronized EEG reactions elicited by sensory stimuli and we consider K-complex type synchronization reactions as a "building stone" of the process of falling asleep which contains the whole process in concentrated form. The manifold similarities between the K-complex and the spike-wave pattern are demonstrated. On this basis spike-wave paroxysms can be regarded as an epileptic "caricature" of the sleep induction momentum reflected in the K-complex phenomenon. Hence, the GESw is the epileptic disorder of the sleep promotion function. This hypothesis resolves and explains many contradictory features of our knowledge about this mechanism and gives a new biologically oriented framework for further research. In the light of the hypothesis it has been attempted to interpret some of the characteristic features of the GESw: the genetic determination, the age dependency, the link with the sleep-waking cycle as well as the functional-anatomical characteristics and the symptoms of the seizures.

Effects of beta-endorphin and morphine on the sleep-wakefulness behavior of cats.

Abstract: The effects of beta-endorphin and of morphine SO4 (0.5 microgram and 2.0 microgram, respectively, injected intraventricularly) upon the sleep-wakefulness behavior of cats were examined. Both agents produced insomnia. Deep slow wave sleep was sharply inhibited, and rapid eye movement (REM) sleep was entirely suppressed. Light slow wave sleep, occurring in brief, isolated episodes, became the most abundant stage of sleep. The nuchal electromyogram was markedly increased after both agents. Naloxone (100 microgram/kg), injected subcutaneously 30 min before beta-endorphin or morphine SO4, entirely reversed these agents' effects on the two stages of slow wave sleep, and antagonized the exaggerated electromyogram. But naloxone did not counteract the REM-suppressant effect of either beta-endorphin or morphine SO4. Total sleep time reverted towards control values after naloxone pretreatment, but not entirely; the difference may be due to the persistent deficit of REM sleep. The data may indicate an involvement of an inner opioid in the regulation of sleep and wakefulness in the cat, and may point to a role for more than one endorphin receptor in the effects of opioids on the states of vigilance in cats.

Hibernation at moderate temperatures: a continuation of slow wave sleep.

Abstract: Golden-mantled ground squirrels (Citellus lateralis) displayed virtually continuous electrophysiological states of sleep when hibernating at moderate ambient temperatures (22°C). Rapid-eye-movement sleep progressively diminished with the fall in body temperature so that at a body temperature of 23°C it was completely absent. At this temperature hibernation was characterized by slow wave sleep isomorphic with slow wave sleep episodes at non-hibernating (euthermic) body temperatures.

A comparative study of the diagnosis value of drug-induced sleep EEGs and sleep EEGs following sleep deprivation in patients with complex partial seizures.

Abstract: The purpose of the study was to investigate whether the sleep EEG after sleep deprivation has a stronger provocative effect than the drug-induced sleep EEG. For this purpose a sleep EEG, induced by 2 mg/kg body weight of promazine hydrochloride, was recorded. On the following day a sleep EEG of the same patient was recorded after sleep deprivation of 24--26 h. If only patients whose wake EEGs were free from epileptic activity are considered, the rate of provocation was 58%. As epileptic activity could be recorded even in the sleep EEG without sleep deprivation in 45%, the advantage gained by recording a sleep EEG after sleep deprivation (52%) is only relatively small. The occurrence of epileptic activity was shown to be significantly more frequent amongst women and those who developed epilepsy at a younger age. For practical purposes it is recommended that for those patients whose wake EEGs are free from epileptic activity, a sleep EEG--possibly drug-induced--should be recorded. Only in instances where epileptic activity can not then be recorded should a wake EEG after sleep deprivation be carried out, and followed immediately, if necessary, by a sleep EEG.

Sleep-inducing effects of three hypnotics in a new model of insomnia in rats.

Abstract: Sleep-inducing effects of hypnotic drugs are difficult to demonstrate in rats because of high baseline sleep times. Most increases in slow wave sleep (SWS) following the administration of hypnotics have been found to be at the expense of REM sleep rather than waking. In the first experiment we found that rats chronically implanted with electrodes for recording ECoG and EMG slept significantly less during the first two hours of the dark period when housed under 16-hr light 8-hr dark (16L/8D) than when housed under 12L/12D conditions. The second experiment examined the effects of flurazepam, phenobarbital and thalidomide administered orally at the onset of the two-hour period of increased waking resulting from the 16L/8D lighting. All three drugs caused dose-dependent reductions in waking and increases in SWS with no alterations in REM% of total sleep time. Sleep onset latency was also significantly was also significantly reduced by all three drugs. As in man, flurazepam was the most potent, and thalidomide was the least potent of the hypnotics in rats.