Showing papers on "Slow-wave sleep published in 1997"

Regional cerebral blood flow throughout the sleep-wake cycle. An H2(15)O PET study

Abstract: To assess dynamic changes in brain function throughout the sleep-wake cycle, CBF was measured with H2(15)O and PET in 37 normal male volunteers: (i) while awake prior to sleep onset; (ii) during Stage 3-4 sleep, i.e. slow wave sleep (SWS); (iii) during rapid eye movement (REM) sleep; and (iv) upon waking following recovery sleep. Subjects were monitored polysomnographically and PET images were acquired throughout the course of a single night. Stage-specific contrasts were performed using statistical parametric mapping. Data were analysed in repeated measures fashion, examining within-subject differences between stages [pre-sleep wakefulness-SWS (n = 20 subjects); SWS-post-sleep wakefulness (n = 14); SWS-REM sleep (n = 7); pre-sleep wakefulness-REM sleep (n = 8); REM sleep-post-sleep wakefulness (n = 7); pre-sleep wakefulness-post-sleep wakefulness (n = 20)]. State dependent changes in the activity of centrencephalic regions, including the brainstem, thalamus and basal forebrain (profound deactivations during SWS and reactivations during REM sleep) are consistent with the idea that these areas are constituents of brain systems which mediate arousal. Shifts in the level of activity of the striatum suggested that the basal ganglia might be more integrally involved in the orchestration of the sleep-wake cycle than previously thought. State-dependent changes in the activity of limbic and paralimbic areas, including the insula, cingulate and mesial temporal cortices, paralleled those observed in centrencephalic structures during both REM sleep and SWS. A functional dissociation between activity in higher order, heteromodal association cortices in the frontal and parietal lobes and unimodal sensory areas of the occipital and temporal lobes appeared to be characteristic of both SWS and REM sleep. SWS was associated with selective deactivation of the heteromodal association areas, while activity in primary and secondary sensory cortices was preserved. SWS may not, as previously thought, represent a generalized decrease in neuronal activity. On the other hand, REM sleep was characterized by selective activation of certain post-rolandic sensory cortices, while activity in the frontoparietal association cortices remained depressed. REM sleep may be characterized by activation of widespread areas of the brain, including the centrencephalic, paralimbic and unimodal sensory regions, with the specific exclusion of areas which normally participate in the highest order analysis and integration of neural information. Deactivation of the heteromodal association areas (the orbital, dorsolateral prefrontal and inferior parietal cortices) constitutes the single feature common to both non-REM and REM sleep states, and may be a defining characteristic of sleep itself. The stages of sleep could also be distinguished by characteristic differences in the relationships between the basal ganglia, thalamic nuclei and neocortical regions of interest.

Adenosine: a mediator of the sleep-inducing effects of prolonged wakefulness.

Abstract: Both subjective and electroencephalographic arousal diminish as a function of the duration of prior wakefulness. Data reported here suggest that the major criteria for a neural sleep factor mediating the somnogenic effects of prolonged wakefulness are satisfied by adenosine, a neuromodulator whose extracellular concentration increases with brain metabolism and which, in vitro, inhibits basal forebrain cholinergic neurons. In vivo microdialysis measurements in freely behaving cats showed that adenosine extracellular concentrations in the basal forebrain cholinergic region increased during spontaneous wakefulness as contrasted with slow wave sleep; exhibited progressive increases during sustained, prolonged wakefulness; and declined slowly during recovery sleep. Furthermore, the sleep-wakefulness profile occurring after prolonged wakefulness was mimicked by increased extracellular adenosine induced by microdialysis perfusion of an adenosine transport inhibitor in the cholinergic basal forebrain but not by perfusion in a control noncholinergic region.

Effects of early and late nocturnal sleep on declarative and procedural memory

Abstract: Recall of paired-associate lists (declarative memory) and mirror-tracing skills (procedural memory) was assessed after retention intervals defined over early and late nocturnal sleep. In addition, effects of sleep on recall were compared with those of early and late retention intervals filled with wakefulness. Twenty healthy men served as subjects. Saliva cortisol concentrations were determined before and after the retention intervals to determine pituitary-adrenal secretory activity. Sleep was determined somnopolygraphically. Sleep generally enhanced recall when compared with the effects of corresponding retention intervals of wakefulness. The benefit from sleep on recall depended on the phase of sleep and on the type of memory: Recall of paired-associate lists improved more during early sleep, and recall of mirror-tracing skills improved more during late sleep. The effects may reflect different influences of slow wave sleep (SWS) and rapid eye movement (REM) sleep since time in SWS was 5 times longer during the early than late sleep retention interval, and time in REM sleep was twice as long during late than early sleep (p < 0.005). Changes in cortisol concentrations, which independently of sleep and wakefulness were lower during early retention intervals than late ones, cannot account for the effects of sleep on memory. The experiments for the first time dissociate specific effects of early and late sleep on two principal types of memory, declarative and procedural, in humans.

Functional neuroanatomy of human slow wave sleep.

Abstract: The distribution of regional cerebral blood flow (rCBF) was estimated during sleep and wakefulness by using H215O positron emission tomography (PET) and statistical parametric mapping. A group analysis on 11 good sleepers (8 with steady slow wave sleep, SWS) showed a significant negative correlation between the occurrence of SWS and rCBF in dorsal pons and mesencephalon, thalami, basal ganglia, basal forebrain/hypothalamus, orbitofrontal cortex, anterior cingulate cortex, precuneus, and, on the right side, in a region that follows the medial aspect of the temporal lobe. Given the known decrease in global cerebral blood flow levels during SWS, these negative correlations suggest that rCBF is decreased significantly more in these cerebral areas than in the rest of the brain. The marked rCBF decreases in the pons, mesencephalon, thalamic nuclei, and basal forebrain reflect their close implication in the generation of SWS rhythms. The influence of these rhythms on the telencephalon usually are thought to be global and homogeneous. In contrast, our results show that rCBF is decreased more in some cortical areas (especially in orbitofrontal cortex) than in the rest of the cortex. We hypothesize that cellular processes taking place during SWS might be modulated differently in these regions. Given the functions of the ventromedial frontal areas, we surmise that SWS might be particularly critical for the adaptation of behavior to environmental pressures. This hypothesis is supported indirectly by results of sleep deprivation experiments.

Regional Cerebral Blood Flow Changes as a Function of Delta and Spindle Activity during Slow Wave Sleep in Humans

Abstract: In the present study, we investigated changes in regional cerebral blood flow (rCBF) in humans during the progression from relaxed wakefulness through slow wave sleep (SWS). These changes were examined as a function of spindle (12–15 Hz) and δ (1.5–4.0 Hz) electroencephalographic (EEG) activity of SWS. rCBF was studied with positron emission tomography (PET) using the H2 15O bolus method. A maximum of six 60 sec scans were performed per subject during periods of wakefulness and stages 1–4 of SWS, as determined by on-line EEG monitoring. Spectral analysis was performed off-line on the EEG epochs corresponding to the scans for computation of activity in specific frequency bands. The relationship between EEG frequency band activity and normalized rCBF was determined by means of a voxel-by-voxel analysis of covariance. δ activity covaried negatively with rCBF most markedly in the thalamus and also in the brainstem reticular formation, cerebellum, anterior cingulate, and orbitofrontal cortex. After the effect of δ was removed, a significant negative covariation between spindle activity and the residual rCBF was evident in the medial thalamus. These negative covariations may reflect the disfacilitation and active inhibition of thalamocortical relay neurons in association with δ and spindles, as well as the neural substrates underlying the progressive attenuation of sensory awareness, motor responsiveness, and arousal that occur during SWS. δ activity covaried positively with rCBF in the visual and auditory cortex, possibly reflecting processes of dream-like mentation purported to occur during SWS.

Effects of sleep and sleep stage on epileptic and nonepileptic seizures

Abstract: Summary: Purpose: Previous studies of patients with epilepsy and animal models of epilepsy suggest that sleep increases the frequency, duration, and secondary generalization of seizures. This information is, however, incomplete. Methods: We retrospectively examined video-EEG monitoring reports from our comprehensive epilepsy center. We recorded seizure type, site of onset (for partial seizures), sleep state at onset, and whether partial seizures secondarily generalized. Seizures arising from sleep were then reviewed to determine sleep state. Results: We analyzed 1,116 seizures in 188 patients. Thirty-five percent of complex partial seizures (CPSs) starting during sleep underwent secondary generalization compared with 18% in wakefulness (p < 0.0001). Frontal lobe CPSs secondarily generalized at equal rates during sleep (22%) and wakefulness (20%), but temporal lobe CPSs generalized much more frequently during sleep (45%) than in wakefulness (19%; p < 0,0001). Frontal lobe seizures were more likely to occur during sleep (37%) than were temporal lobe seizures (26%; p = 0.0068). CPSs were more frequent in stages 1 and 2 and occurred rarely during REM. Seizures starting during slow-wave sleep were significantly longer than seizures starting during wakefulness or stage 2 sleep. Psychogenic nonepileptic seizures (PNESs) were rare between midnight and 6 a.m. and never occurred during sleep. Conclusions: Sleep has a pronounced effect on secondary generalization of partial seizures, especially those of temporal lobe origin. Frontal lobe seizures occur more often during sleep than do temporal lobe seizures, and occurrence during sleep helps to distinguish PNESs from CPSs.

Sleep and morningness-eveningness in the 'middle' years of life (20-59 y).

Abstract: The following four issues were assessed in a group of 110 adults between the age of 20 and 59y: (1) the effect of age (regarded as a continuous variable) on polysomnographic sleep characteristics, habitual sleep-diary patterns, and subjective sleep quality; (2) the effects of age on morningness-eveningness; (3) the effects of morningness-eveningness on sleep, after controlling for the effects of age; and (4) the role of morningness-eveningness as a mediator of the age and sleep relationship. Increasing age was related to earlier habitual waketime, earlier bedtime, less time in bed and better mood and alertness at waketime. In the laboratory, increasing age was associated with less time asleep, increased number of awakenings, decreased sleep efficiency, lower percentages of slow-wave sleep (SWS) and rapid eye movement (REM) sleep, higher percentages of Stage 1 and 2, shorter REM latency and reduced REM activity and density. Increasing age was also associated with higher morningness scores. After controlling for the effects of age, morningness was associated with earlier waketime, earlier bedtime, less time in bed, better alertness at waketime, less time spent asleep, more wake in the last 2 h of sleep, decreased REM activity, less stage REM (min and percentage), more Stage 1 (min and percentage) and fewer minutes of Stage 2. For one set of variables (night time in bed, waketime, total sleep time, wake in the last 2 h of sleep and minutes of REM and REM activity), morningness-eveningness accounted for about half of the relationship between age and sleep. For another set of variables (bedtime, alertness at waketime, percentages of REM and Stage 1), morningness-eveningness accounted for the entire relationship between age and sleep. In conclusion, age and morningness were both important predictors of the habitual sleep patterns and polysomnographic sleep characteristics of people in the middle years of life (20-59 y).

Respiratory arousal from sleep: mechanisms and significance.

Abstract: The mechanisms by which respiratory stimuli induce arousal from sleep and the clinical significance of these arousals have been explored by numerous studies in the last two decades. Evidence to date suggests that the arousal stimulus in nonrapid eye movement sleep (NREM) is related to the level of inspiratory effort rather than the individual stimuli that contribute to ventilatory drive. A component of the arousal stimulus proportional to the level of inspiratory effort may originate in mechanoreceptors either in the upper airway or respiratory pump. Medullary centers responsible for ventilatory drive may also send a signal proportionate to the level of drive to higher centers in the brain which are responsible for arousal. Thus, the arousal stimulus may consist of multiple components, each increasing as inspiratory effort increases. The level of effort triggering arousal is an index of the arousability of the brain (arousal threshold). A deeper stage of sleep, central nervous system depressants, prior sleep fragmentation, and the presence of obstructive sleep apnea (OSA) have been observed to increase the arousal threshold to airway occlusion. Less information is available concerning the mechanisms of arousal from rapid eye movement (REM) sleep. While REM sleep is associated with the longest obstructive apneas in patients with OSA, normal human subjects appear to have a similar or lower arousal threshold to respiratory stimuli in REM compared to NREM sleep. Recent studies have challenged the assumption that the termination of all obstructive apnea is dependent on arousal from sleep. Improvements in methods to detect and quantitate changes in the cortical electroencephalogram (EEG) may better define the relationship between arousal and apnea termination. This may result in improved criteria for identifying EEG changes of clinical significance. While little is known concerning the mechanisms of arousal in central sleep apnea, arousal may play an important role in inducing this type of apnea in some patients.

Variation of electroencephalographic activity during non-rapid eye movement and rapid eye movement sleep with phase of circadian melatonin rhythm in humans

Abstract: 1. The circadian pacemaker regulates the timing, structure and consolidation of human sleep. The extent to which this pacemaker affects electroencephalographic (EEG) activity during sleep remains unclear. 2. To investigate this, a total of 1.22 million power spectra were computed from EEGs recorded in seven men (total, 146 sleep episodes; 9 h 20 min each) who participated in a one-month-long protocol in which the sleep-wake cycle was desynchronized from the rhythm of plasma melatonin, which is driven by the circadian pacemaker. 3. In rapid eye movement (REM) sleep a small circadian variation in EEG activity was observed. The nadir of the circadian rhythm of alpha activity (8.25-10.5 Hz) coincided with the end of the interval during which plasma melatonin values were high, i.e. close to the crest of the REM sleep rhythm. 4. In non-REM sleep, variation in EEG activity between 0.25 and 11.5 Hz was primarily dependent on prior sleep time and only slightly affected by circadian phase, such that the lowest values coincided with the phase of melatonin secretion. 5. In the frequency range of sleep spindles, high-amplitude circadian rhythms with opposite phase positions relative to the melatonin rhythm were observed. Low-frequency sleep spindle activity (12.25-13.0 Hz) reached its crest and high-frequency sleep spindle activity (14.25-15.5 Hz) reached its nadir when sleep coincided with the phase of melatonin secretion. 6. These data indicate that the circadian pacemaker induces changes in EEG activity during REM and non-REM sleep. The changes in non-REM sleep EEG spectra are dissimilar from the spectral changes induced by sleep deprivation and exhibit a close temporal association with the melatonin rhythm and the endogenous circadian phase of sleep consolidation.

Simultaneous stimulation of slow-wave sleep and growth hormone secretion by gamma-hydroxybutyrate in normal young Men.

Abstract: The aim of this study was to investigate, in normal young men, whether gamma-hydroxybutyrate (GHB), a reliable stimulant of slow-wave (SW) sleep in normal subjects, would simultaneously enhance sleep related growth hormone (GH) secretion. Eight healthy young men participated each in four experiments involving bedtime oral administration of placebo, 2.5, 3.0, and 3.5 g of GHB. Polygraphic sleep recordings were performed every night, and blood samples were obtained at 15-min intervals from 2000 to 0800. GHB effects were mainly observed during the first 2 h after sleep onset. There was a doubling of GH secretion, resulting from an increase of the amplitude and the duration of the first GH pulse after sleep onset. This stimulation of GH secretion was significantly correlated to a simultaneous increase in the amount of sleep stage IV. Abrupt but transient elevations of prolactin and cortisol were also observed, but did not appear to be associated with the concomitant stimulation of SW sleep. Thyrotropin and melatonin profiles were not altered by GHB administration. These data suggest that pharmacological agents that reliably stimulate SW sleep, such as GHB, may represent a novel class of powerful GH secretagogues.

Melatonin and the circadian regulation of sleep initiation, consolidation, structure, and the sleep EEG

Abstract: The endogenous circadian rhythm of melatonin, driven by the suprachiasmatic nucleus, exhibits a close association with the endogenous circadian component of the sleep propensity rhythm and the endogenous circadian component of the variation in electroencephalogram (EEG) oscillations such as sleep spindles and slow waves. This association is maintained even when the sleep-wake cycle is desynchronized from the endogenous circadian rhythm of melatonin. Administration of melatonin during the day increases daytime sleep propensity as indexed by both the latency to sleep onset and sleep consolidation. The EEG during daytime sleep after melatonin administration exhibits characteristics reminiscent of the nocturnal sleep EEG, that is, increased sleep spindle activity and reduced slow-wave sleep and slow-wave activity, as detected by quantitative EEG analysis. Administration of higher doses of melatonin (5 mg or more) prior to nocturnal sleep results in an increase in rapid eye movement (REM) sleep. These data demonstrate that melatonin exerts effects on the main characteristics of human sleep, that is, latency to sleep onset, sleep consolidation, slow waves, sleep spindles, and REM sleep. There is a need for further studies using physiological doses and delivery systems that generate physiological plasma melatonin profiles to firmly establish the role of the endogenous circadian rhythm of melatonin in the circadian regulation of sleep.

Good sleep--its timing and physiological sleep characteristics.

Abstract: SUMMARY The present study used short sleep episodes to explore the relation between subjective sleep quality, timing and physiological content of sleep. Eight subjects participated in 18 4-h sleep episodes to provide 4, 8, and 12 h of prior time awake before bedtimes at six different times of day in a sleep laboratory insulated from environmental disturbances. The results were analysed by ANOVAs and multiple regression techniques. Subjective sleep quality, calmness of sleep, ease of falling asleep, ability to ‘sleep through’, number of awakenings, and sleep latency showed a significant pattern of ‘better’ sleep with increasing prior time awake and with closeness to the circadian minimum (nadir) of rectal temperature (morning hours). ‘Ease of awakening’ in contrast, ‘decreased’ with increasing time awake and with closeness to the nadir/ morning hours. Multiple regression analysis showed that subjective sleep quality was predicted by subjective calmness of sleep and ease of falling asleep, among the subjective measures, and by total sleep time (TST) and slow-wave sleep (SWS – stages 3 +4) among the physiological sleep measures. The subjective ease of awakening was predicted by slow-wave sleep (negatively) and the circadian maximum of rectal temperature. The results indicate that the duration of wakefulness prior to sleep and the timing of sleep determine its physiological expression, which in turn determines its subjective impression.

Excitation of the brain stem pedunculopontine tegmentum cholinergic cells induces wakefulness and REM sleep.

Abstract: Datta, Subimal and Donald F. Siwek. Excitation of the brain stem pedunculopontine tegmentum cholinergic cells induces wakefulness and REM sleep. J. Neurophysiol. 77: 2975–2988, 1997. Considerable e...

Positive correlations between cerebral protein synthesis rates and deep sleep in Macaca mulatta.

Abstract: Local rates of cerebral protein synthesis (ICPSleu) were determined with the autoradiographic L-[1-14C]leucine method in seven awake and seven asleep, adult rhesus monkeys conditioned to sleep in a restraining chair in a darkened, ventilated chamber while EEG, EOG, and EMG were monitored. Prior to the period of measurement all animals slept for 1-4 h. Controls were awakened after at least one period of rapid-eye-movement (REM) sleep. Experimental animals were allowed to remain asleep, and they exhibited non-REM sleep for 71-99% of the experimental period. Statistically significant differences in ICPSleu between control and experimental animals were found in four of the 57 regions of brain examined, but these effects may have occurred by chance. In the sleeping animals, however, correlations between ICPSleu and percent time in deep sleep were positive in all regions and were statistically significant (P < or = 0.05) in 35 of the regions. When time in deep sleep was weighted for the integrated specific activity of leucine in grey matter, positive correlations were statistically significant (P < or = 0.05) in 18 regions in the experimental animals. These results suggest that rates of protein synthesis are increased in many regions of the brain during deep sleep compared with light sleep.

The GABAA agonist THIP produces slow wave sleep and reduces spindling activity in NREM sleep in humans.

Abstract: Recent studies in the rat demonstrated that systemic administration of muscimol and THIP, both selective GABAA receptor agonists, elevates slow wave activity in the EEG during non-rapid eye movement (NREM) sleep. In this placebo-controlled study, we assessed the influence of an oral dose of 20 mg THIP on nocturnal sleep in young healthy humans. Compared to placebo, THIP increased slow wave sleep by about 25 min. Spectral analysis of the EEG within NREM sleep revealed significant elevations in the lower frequencies (< 8 Hz) and reductions in the spindle frequency range (approximately 10-16 Hz). In accordance with previous findings in the rat, these data imply that GABAA agonists promote deep NREM sleep, without suppressing REM sleep. These effects are opposite to those induced by agonistic modulators of GABAA receptors such as benzodiazepines and are at variance with established mechanisms according to which GABAA agonists and modulatory agonists would have similar effects. The sleep response to GABAA agonists is highly similar to that evoked by sustained wakefulness, suggesting that GABAA receptors may be implicated in the homeostatic regulation of sleep.

Slow-wave sleep: do young adult men and women age differently?

Abstract: The differential effects of ageing on polysomnographic and EEG spectral characteristics of sleep were explored in men and women between the ages of 20 and 40. Men and women in their twenties were found to have similar percentages of slow-wave sleep (SWS) (% Stage 3 and 4) and mean EEG slow wave activity (quantified by spectral analysis). Significant reductions in the percentage of SWS and mean slow wave activity over the night occurred in men during their thirties but not in the women. This suggests that gender difference in SWS may emerge between age 30 and 40 in young adults. Men in this sample were also found to have significant increases in Stage 2 sleep, and decreases in REM sleep time, REM activity, REM density and REM intensity. No significant effects of age were found for women in any visually scored sleep variables. Both men and women had age related reductions in spectral power in the spindle frequencies. Taken together, these findings suggest that the sleep of men and women over age 20-40 may age differently.

Sleep ontogenesis revisited: a longitudinal 24-hour home polygraphic study on 15 normal infants during the first two years of life.

Abstract: The sleep organization of 15 normal infants (seven boys, eight girls) was studied at their homes during six 24-hour periods, i.e. at 3, 6, 9, 12, 18, and 24 months of age, using the Oxford Medical System. Sleep states and stages were scored visually at 30-second intervals, according to Rechtschaffen and Kales' criteria, adapted for children by Guilleminault. All sleep parameters were analyzed for the entire 24-hour period, i.e. during both the nocturnal and the diurnal part of the nycthemere. The results showed a continuous decrease in total sleep time, rapid eye movement (REM) sleep, and indeterminate sleep, and also an increase in waking time, quiet sleep, and stages 1 and 2 sleep. Except for slow-wave sleep, which remained very stable for the different ages, analysis of variance applied to the data showed clear age and day-night effects on sleep ontogenesis. Modifications with age were more precocious and more pronounced for the diurnal part of the nycthemere, especially as regards REM sleep. For the nocturnal part, there was a significant increase in sleep efficiency and in the length of the REM period after 12 months of age, while total sleep duration and number of awakenings decreased. In addition to normative data for clinical use, this study provides three new interesting results related to the maturation of sleep mechanisms and functions: 1) the high stability of the percentage of slow-wave sleep along these 2 years, 2) the presence (from 12 months of age) of a stage 2/REM sleep ratio equal to one, and a sleep change occuring earlier, during the diurnal rather than the nocturnal part of the nycthemere. The first two points could be regarded as indexes of sleep maturation reflecting developmental and neurophysiological changes in central nervous system structures. The third point underlines the importance of the circadian rhythm and the concept of "experience" in the maturation of sleep.

Development of REM and slow wave sleep in the rat

Abstract: Active sleep (AS) in the neonate has been considered to be an immature form of rapid eye movement (REM) sleep. Quiet sleep (QS) has been thought to represent an immature form of slow wave sleep (SWS). To determine the relationship between the behaviorally determined states of AS and QS and electrographically determined REM sleep and SWS, we examined sleep ontogeny in the developing rat using an experimental routine that permitted long-term recordings and minimized the effects of maternal separation. Under these conditions, a transient state that included electroencephalographic slow wave activity and phasic motor activity was eventually replaced with the mature SWS pattern. Our work suggests that neonatal QS is not an immature form of SWS and that AS is best considered as an undifferentiated behavioral state from which both SWS and REM sleep develop.

Generalized anxiety and sleep architecture: A polysomnographic investigation.

Abstract: The sleep of 15 adult subjects who reported heightened generalized anxiety in the absence of other psychiatric syndromes and a 15-adult contrast group were studied by means of nocturnal polysomnography. Analysis of polysomnography variables revealed a significant discriminant function that accounted for 79% of the variance between groups, indicating that high-anxiety/worry subjects took longer to fall asleep, had a smaller percentage of deep (slow-wave) sleep, and more frequent transitions into light sleep [stage 1 nonrapid eye movement (NREM)]. Additional analyses indicated that high-anxiety/worry subjects had a greater percentage of light sleep, more early microarousals, a lower rapid eye movement (REM) density relative to low-anxiety subjects. These subjects also showed more electrodermal storming when slow-wave sleep and REM sleep variables were covaried. Results indicated disrupted sleep depth and continuity similar to that documented in clinical anxiety disorder patients and distinct from that of depressed patients. These results indicate that generalized anxiety and worry in otherwise healthy individuals may act to produce a clinically significant sleep disturbance in the absence of other psychiatric symptoms.

Effects of training volume on sleep, psychological, and selected physiological profiles of elite female swimmers.

Abstract: Excessive training is reported to cause sleep disturbances and mood changes. We examined sleep and psychological changes in female swimmers across a competitive swimming season, that is, at the start of the season (onset), during peak training period (peak), and after a precompetition reduction in training (taper). For each phase, polysomnographic recordings, body composition, psychological parameters, and swimming performance were obtained. A daily training log and sleep diary were maintained for the entire study period. Sleep onset latency (SOL), time awake after sleep onset, total sleep time (TST), and rapid eye movement (REM) sleep times were similar at all three training levels. Slow wave sleep (SWS) formed a very high percentage of total sleep in the onset (26%) and peak (31%) training periods, but was significantly reduced following precompetition taper (16%), supporting the theory that the need for restorative SWS is reduced with reduced physical demand. The number of movements during sleep was significantly higher at the higher training volumes, suggesting some sleep disruption. In contrast to other studies, mood deteriorated with a reduction in training volume and/or impending competition.

Neuropeptides and human sleep

Abstract: Results from preclinical studies have validated the participation of neuropeptides in sleep regulation. In recent human and clinical studies it has been shown that peripheral administration of various peptides results in specific changes in the sleep electroencephalogram in humans. Furthermore, it has been demonstrated that certain peptides are common regulators of the electrophysiological and neuroendocrine components of sleep. It is now well established that the balance between the neuropeptides growth hormone-releasing hormone (GHRH) and cortico-tropin-releasing hormone (CRH) plays a key role in normal and pathological sleep regulation. In young normal subjects. GHRH stimulates slow-wave sleep and growth hormone secretion but inhibits cortisol release, whereas CRH has the opposite effect. During normal aging and during acute depression, the GHRH:CRH ratio is changed in favor of CRH, resulting in disturbances in sleep endocrine activity. In addition to GHRH, galanin, growth hormone-releasing peptide, and neuropeptide Y also promote sleep, unlike ACTH(4-9), which disturbs sleep. In elderly subjects, sleep deteriorates after acute administration of somatostatin but improves after chronic treatment with vasopressin. Vasoactive intestinal polypeptide decelerates the non-rapid eye movement-rapid eye movement cycle and advances the occurrence of the cortisol nadir. The impact of delta sleep-inducing peptide, cholecystokinin. and thyrotropin-releasing hormone on human sleep regulation is not yet clear. This paper reviews recent work investigating the influence of these various neuropeptides on sleep.

Electrophysiological correlates of higher states of consciousness during sleep in long-term practitioners of the Transcendental Meditation program.

Abstract: Standard ambulatory night sleep electroencephalograph (EEG) of 11 long-term practitioners of the Transcendental Meditation (TM) program reporting "higher states of consciousness" during sleep (the experimental group) was compared to that of nine short-term practitioners and 11 non-practitioners. EEG tracings during stages 3 and 4 sleep showed the experimental group to have: 1) theta-alpha activity simultaneously with delta activity and 2) decreased chin electromyograph (EMG) during deep sleep (p = 0.002) compared to short-term practitioners. Spectral analysis fast Fourier transform (FFT) data of the first three cycles showed that: 3) the experimental subjects had significantly greater theta 2 (6-8 Hz)-alpha 1 (8-10 Hz) relative power during stages 3 and 4 than the combined control groups [t(30) = 5.5, p = 0.0000008] with no difference in time in delta; 4) there was a graded difference across groups during stages 3 and 4 in theta 2-alpha 1 power, with experimentals having greater power than short-term practitioners, who in turn had greater power than non-practitioners [t(30) = 5.08, p = 0.00002]; and 5) experimentals also had increased rapid eye movement (REM) density during REM periods compared to short-term practitioners (p = 0.04). Previous studies have found increased theta-alpha EEG activity during reported periods of "transcendental consciousness" during the TM technique. In the Vedic tradition, as described by Maharishi Mahesh Yogi, transcendental consciousness is the first of a sequence of higher states. The maintenance of transcendental consciousness along with deep sleep is said to be a distinctive criterion of further, stabilized higher states of consciousness. The findings of this study are interpreted as physiological support for this model.