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PubMed1999

Age-related effects of scopolamine on REM sleep regulation in normal control subjects: relationship to sleep abnormalities in depression.

In order to assess the influence of development on the regulation of rapid eye movement (REM) sleep by cholinergic systems, the REM sleep responses to scopolamine were assessed in five normal adolescent and seven adult control subjects in this preliminary investigation. Subjects were studied on two separate occasions for three consecutive nights. Subjects received placebo or scopolamine (1.5 ug/kg, i.m.) on night 2; night 3 was considered the "recovery" night. As expected, scopolamine delayed REM latency and suppressed REM sleep on night 2 in both the adolescents and adults. Subtle developmental differences occurred, with scopolamine having a tendency to suppress REM sleep less effectively in younger subjects. On night 3, REM latency was shortened and REM sleep was increased to comparable extent in both the adolescents and adults. The comparable REM sleep responses to scopolamine between normal adolescents and adults, particularly on night 3, are discussed in relation to the age-related expression of REM sleep abnormalities in depression.

Adolescent↗
PubMed2000

A review of mentation in REM and NREM sleep: "covert" REM sleep as a possible reconciliation of two opposing models.

Numerous studies have replicated the finding of mentation in both rapid eye movement (REM) and nonrapid eye movement (NREM) sleep. However, two different theoretical models have been proposed to account for this finding: (1) a one-generator model, in which mentation is generated by a single set of processes regardless of physiological differences between REM and NREM sleep; and (2) a two-generator model, in which qualitatively different generators produce cognitive activity in the two states. First, research is reviewed demonstrating conclusively that mentation can occur in NREM sleep; global estimates show an average mentation recall rate of about 50% from NREM sleep--a value that has increased substantially over the years. Second, nine different types of research on REM and NREM cognitive activity are examined for evidence supporting or refuting the two models. The evidence largely, but not completely, favors the two-generator model. Finally, in a preliminary attempt to reconcile the two models, an alternative model is proposed that assumes the existence of covert REM sleep processes during NREM sleep. Such covert activity may be responsible for much of the dreamlike cognitive activity occurring in NREM sleep.

Brain↗
PubMed2002

Sleeping with the hypothalamus: emerging therapeutic targets for sleep disorders.

Delineating the basic mechanisms that regulate sleep will likely result in the development of better treatments for sleep disorders. The hypothalamus is now recognized as a key center for sleep regulation, with hypothalamic neurotransmitter systems providing the framework for therapeutic advances. An increased awareness of the close interaction between sleep and homeostatic systems is also emerging. Progress has occurred in the understanding of narcolepsy--molecular techniques have identified the lateral hypothalamic hypocretin (orexin) neuropeptide system as key to the disorder. Other sleep disorders are now being tackled in the same way and are likely to yield to efforts combining basic and clinical research. Here we highlight the role of the hypothalamus in sleep physiology and discuss neurotransmitter systems, such as adenosine, dopamine, GABA, histamine and hypocretin, that may have therapeutic applications for sleep disorders.

Animals↗
PubMed2003

Effect of sleep and sleep deprivation on serotonergic neurotransmission in the hippocampus: a combined in vivo microdialysis/EEG study in rats.

Brainstem serotonergic neurotransmission is implicated in sleep regulation. However, the role of serotonin (5-HT) in forebrain regions in sleep-wake mechanisms is still unclear. Here, we have investigated, using a combined in vivo microdialysis/electroencephalogram method, the relationship between hippocampal 5-HT levels and sleep-wake behaviour in the rat. A clear-cut relationship was found between hippocampal 5-HT levels and vigilance state. The highest levels of 5-HT were observed during wakefulness, whereas a progressive decrease of 5-HT going from nonrapid eye movement sleep to rapid eye movement sleep was found. Sleep deprivation (SD) causes a transient enhancement of mood in depressed patients. Given the putative role of 5-HT in the aetiology of depression and the therapeutical efficacy of selective serotonin reuptake inhibitors in this illness, we also studied hippocampal 5-HT during 4 h of SD and during the subsequent recovery period. During the whole SD period, 5-HT levels were elevated substantially when compared to 5-HT levels during basal wakefulness. However, no changes in 5-HT levels and the relationship between hippocampal 5-HT and vigilance state were found during the subsequent recovery period. As SD is a potentially stressful experience and glucocorticoids are involved in the regulation of serotonergic neurotransmission and sleep, we investigated the effects of SD on free corticosterone levels. SD caused a marked rise in free corticosterone levels. However, the effects of SD on 5-HT seem not to be mediated by this hormone, because adrenalectomy did not affect the rise in hippocampal 5-HT during SD. We hypothesize that the elevated hippocampal 5-HT levels during SD may participate in the transient mood enhancing properties of forced wakefulness observed in depressed patients.

Adrenalectomy↗
PubMed2005

Idiopathic chronic sleep onset insomnia in attention-deficit/hyperactivity disorder: a circadian rhythm sleep disorder.

To investigate whether ADHD-related sleep-onset insomnia (SOI) is a circadian rhythm disorder, we compared actigraphic sleep estimates, the circadian rest-activity rhythm, and dim light melatonin onset (DLMO) in ADHD children having chronic idiopathic SOI with that in ADHD children without sleep problems. Participants were 87 psychotropic-medication-naïve children, aged 6 to 12 yrs, with rigorously diagnosed ADHD and SOI (ADHD-SOI) and 33 children with ADHD without SOI (ADHD-noSOI) referred from community mental health institutions and pediatric departments of non-academic hospitals in The Netherlands. Measurements were 1 wk, 24 h actigraphy recordings and salivary DLMO. The mean (+/-SD) sleep onset time was 21:38 +/- 0:54 h in ADHD-SOI, which was significantly (p < 0.001) later than that of 20:49 +/- 0:49 h in ADHD-noSOI. DLMO was significantly later in ADHD-SOI (20:32 +/- 0:55 h), compared with ADHD-noSOI (19:47 +/- 0:49 h; p < 0.001). Wake-up time in ADHD-SOI was later than in ADHD-noSOI (p = 0.002). There were no significant between-group differences in sleep maintenance, as estimated by number of wake bouts and activity level in the least active 5 h period, or inter- and intradaily rhythm variability. We conclude that children with ADHD and chronic idiopathic sleep-onset insomnia show a delayed sleep phase and delayed DLMO, compared with ADHD children without SOI.

Attention Deficit Disorder with Hyperactivity↗
PubMed1992

Enhanced slow-wave activity within NREM sleep in the cortical and subcortical EEG of the cat after sleep deprivation.

Electroencephalograms (EEGs) of the cortex and of seven subcortical structures were recorded during two baseline days and during a recovery day following a 12-hour period of sleep deprivation (SD) in eight cats. The EEGs were analyzed by visual scoring and by spectral analysis. The following subcortical structures were studied: hippocampus, amygdala, hypothalamus, nucleus centralis lateralis of the thalamus, septum, nucleus caudatus and substantia nigra. The EEGs of all brain structures exhibited sleep state-dependent changes. In general, slow-wave activity (SWA, 0.5-4.0 Hz) during nonrapid eye movement (NREM) sleep exceeded that of REM sleep. The power spectra (0.5-24.5 Hz) in NREM, as well as the relationship between the power spectra of NREM and REM sleep, differed between the recording sites. Moreover, the rate of increase of SWA in the course of an NREM episode and the rate of decrease of SWA at the transition from NREM to REM sleep differed between the brain structures. During the first 12 hours following SD, the duration of NREM increased due to a prolongation of the NREM episodes. REM increased by a rise in the number of REM episodes. During the same period, the NREM EEG power density in the delta and theta frequencies was enhanced in all brain structures. Furthermore, in all structures the enhancement of SWA was most pronounced at the beginning of the recovery period and gradually declined thereafter. SD also induced a rise in the rate of increase of SWA in the NREM episodes in all recording sites. This indicates that the enhancement of EEG power density was not only due to prolongation of the NREM episodes. The EEG activity during REM was barely affected by the SD. It is concluded that, in all brain structures studied, the EEG during NREM is characterized by high levels of SWA. Furthermore, in each brain structure, SWA within NREM sleep is enhanced after a prolonged vigil. These data may indicate that SWA reflects a recovery process in cortical and subcortical structures.

Animals↗
PubMed1994

Waking electroencephalogram activity as a consequence of sleep and total sleep deprivation in the rat.

Effects of 6 hours of total sleep deprivation (TSD) by gentle handling and 6 hours of sleep on the waking electroencephalogram (EEG) activity of 14 Wistar rats were studied during the lights-on portion of the light-dark cycle under two TSD schedules: a) TSD 0800-1400 hours and sleep 1400-2000 hours, and b) sleep 0800-1400 hours and TSD 1400-2000 hours. EEG was recorded monopolarly from left and right parietals referred to ipsilateral reference electrodes. Spectral analysis was performed on samples of waking EEG during TSD (each 30 minutes) and during sleep (each 60 minutes after enforced awakening). The following significant changes were observed: TSD induced a linear increase in the absolute power of delta (1.46-3.42 Hz) and the full band (1.6-24.9 Hz) and produced a decrease in the interparietal correlation of theta. Sleep induced the opposite results. Theta relative power (power in a band expressed as a percentage of total power between 1.46 and 24.9 Hz) showed a circadian effect. It was higher at 1400 hours than at 0800 and 2000 hours after both sleep and TSD conditions. Six hours of TSD were enough to induce significant changes in the waking EEG regardless of position of TSD in the lights-on period of the light-dark cycle.

Animals↗
PubMed1996

Sleep-disordered breathing and its effects on sleep in infants.

Sleep apnea has been recorded in many infants, but little data exist concerning the amount and range of apnea in infants. We studied 49 infants referred to the sleep disorders unit. Single polysomnographic studies were performed on each infant. We examined the amount of apnea, presence and amount of upper airway obstruction and the sleeping pattern in each infant. Central apnea was common to all infants and varied in amount. Upper airway obstruction, recorded as mixed apnea, was found in 36 infants. Twenty of these infants had only occasional mixed apnea ( < 2 apneas/hour), whereas 16 infants displayed a higher amount of obstruction. All infants were separated into two groups according to amount of apnea and obstruction. Sixteen infants with obstruction plus 3 infants with a high amount of central apnea represented group I. The remaining 30 infants represented group II. Marked differences in the sleeping pattern were found when the groups of infants were separated. Infants from group I had significantly less rapid eye movement (REM) sleep than infants from group II. We conclude that sleep-disordered breathing in infants is associated with disruptions in sleep.

Electrocardiography↗
PubMed1982

Effects of flurazepam on sleep and growth hormone release during sleep in healthy subjects.

We studied the effect of flurazepam, a known suppressor of stages 3 and 4 of sleep, on nocturnal sleep patterns and on growth hormone release immediately following sleep onset in normal young adults. Polysomnography and sampling of growth hormone (every 20 min for 26 h) were performed before and after 2 weeks of nightly flurazepam (30 mg, 8 subjects) or placebo (8 subjects) administration. There were no significant changes in growth hormone release in spite of a significant decrease in stage 4 sleep (69%) and total waking time (46%) and an increase in total sleep time (23%) in the drug group. REM sleep was not changed. These results indicate that the normal GH release following sleep onset continues to occur despite stage 4 suppression by pharmacological means.

Adult↗
PubMed1984

Effect of sleep position on sleep apnea severity.

Thirty male patients evaluated sequentially for sleep apnea syndrome by all-night clinical polysomnography were compared for apnea plus hypopnea index (A + HI) during the time in the side versus time in the back sleep posture. For 24 subjects of this sample, who occupied both major body positions during the evaluation night, the apnea index was found to be twice as high during the time spent sleeping on their backs as it was when they slept in the side position. This difference is reliable and inversely related to obesity. Five patients meeting diagnostic criteria for sleep apnea on an all-night basis fell within normal limits while in the side sleep position. This suggests sleep position adjustment may be a viable treatment for some nonobese sleep apnea patients.

Body Weight↗
PubMedDate not supplied

The role of sleep in changing our minds: a psychologist's discussion of papers on memory reactivation and consolidation in sleep.

The group of papers on memory reactivation and consolidation during sleep included in this volume represents cutting edge work in both animals and humans. They support that the two types of sleep serve different necessary functions. The role of slow wave sleep (SWS) is reactivation of the hippocampal-neocortical circuits activated during a waking learning period, while REM sleep is responsible for the consolidation of this new learning into long-term memory. These studies provide further insights into mechanisms involved in brain plasticity. Robeiro has demonstrated the upregulation of an immediate-early gene (IEG zif 268) to waking levels, which occurs only in REM and only in connection with new learning. McNaughton and his group have identified electrical indicators that the hippocampus and neocortex are talking to each other by testing the coactivation of hippocampal sharp wave bursts in SWS and shifts from down to up states of activation in the neocortex. In human studies Smith's group reports work on individual differences such as intelligence and presleep alcohol that affect postsleep performance, and Stickgold and collaborators report that a short nap will improve performance if it contains REM sleep. Payne and Nadel suggest that the recall benefit associated with REM sleep may be due to its association with increased cortisol levels. These papers are important not only in their individual contributions but also in revitalizing the work coordinating waking and sleep. This promises to further the understanding of how our unique capacity to learn from experience and modify our behavior takes place.

Animals↗
PubMed2006

Cardiorespiratory-based sleep staging in subjects with obstructive sleep apnea.

A cardiorespiratory-based automatic sleep staging system for subjects with sleep-disordered breathing is described. A simplified three-state system is used: Wakefulness (W), rapid eye movement (REM) sleep (R), and non-REM sleep (S). The system scores the sleep stages in standard 30-s epochs. A number of features associated with the epoch RR-intervals, an inductance plethysmography estimate of rib cage respiratory effort, and an electrocardiogram-derived respiration (EDR) signal were investigated. A subject-specific quadratic discriminant classifier was trained, randomly choosing 20% of the subject's epochs (in appropriate proportions of W, S and R) as the training data. The remaining 80% of epochs were presented to the classifier for testing. An estimated classification accuracy of 79% (Cohen's kappa value of 0.56) was achieved. When a similar subject-independent classifier was trained, using epochs from all other subjects as the training data, a drop in classification accuracy to 67% (kappa = 0.32) was observed. The subjects were further broken in groups of low apnoea-hypopnea index (AHI) and high AHI and the experiments repeated. The subject-specific classifier performed better on subjects with low AHI than high AHI; the performance of the subject-independent classifier is not correlated with AHI. For comparison an electroencephalograms (EEGs)-based classifier was trained utilizing several standard EEG features. The subject-specific classifier yielded an accuracy of 87% (kappa = 0.75), and an accuracy of 84% (kappa = 0.68) was obtained for the subject-independent classifier, indicating that EEG features are quite robust across subjects. We conclude that the cardiorespiratory signals provide moderate sleep-staging accuracy, however, features exhibit significant subject dependence which presents potential limits to the use of these signals in a general subject-independent sleep staging system.

Algorithms↗
PubMed2006

Effects of two nights sleep deprivation and two nights recovery sleep on response inhibition.

This study examined the effects of two nights of total sleep deprivation (TSD) and two nights of recovery sleep on response inhibition. Thirty-eight young, healthy adults performed a Go-NoGo task at 14 : 00 after: (1) a normal night of sleep; (2) each of two consecutive nights of TSD; and (3) each of two consecutive nights of recovery sleep; they also performed the task at 05 : 00 during the first night of sleep deprivation. We hypothesized that TSD would lead to an impaired ability to withhold a response that would be reversed with recovery sleep. Subjects did experience a significant increase in false positive responses throughout all of TSD, errors of omission (i.e. missed 'go' targets) were not significant until after the second night of TSD. Both components (withholding a response and automatic responding) of the task returned to baseline levels after one night of recovery sleep. These data suggest that individuals experience difficulty in withholding an inappropriate response during TSD, even when they are able to attend to the incoming stimuli and respond accurately to appropriate stimuli.

Adult↗
PubMed1990

REM sleep without muscle atonia (stage 1-REM) and its relation to delirious behavior during sleep in patients with degenerative diseases involving the brain stem.

Nocturnal sleep was examined in 12 patients with degenerative diseases involving the brain stem and in 2 patients with late cerebellar cortical atrophy (LCCA). A peculiar sleep state, characterized by the concomitant appearance of a low-voltage mixed frequency EEG, rapid eye movements (REMs) and tonic EMG in mental muscles, repeatedly appeared during nocturnal sleep in all of the 12 patients with degenerative diseases involving the brain stem and it was called stage 1-REM after Tachibana et al. In 8 of the 12 patients, delirious or oneiric behavior appeared during, or soon after, the episodes of stage 1-REM. Inner experiences reported by one of the subjects well corresponded to his behavior during the episode of stage 1-REM. Stage 1-REM was not observed during nocturnal sleep of the patients with LCCA. These results indicate that a degenerative lesion in the brain stem induced stage 1-REM and delirious behavior during nocturnal sleep through abolishing muscle atonia of REM sleep and causing dissociation of the functional components characterizing REM sleep.

Aged↗
PubMed1997

Recording of electroencephalograms and electrocardiograms during daytime sleep in trained canines: preparation of the sleeping dogs.

Although respiration in trained canines is well investigated, the process of preparing dogs has not been described in any great detail. Moreover, their daytime patterns of sleep and wakefulness during 1 or 2 h of electroencephalogram (EEG) and electrocardiogram (ECG) recordings are not clear. Therefore, we describe the process of selecting and training dogs, in which we recorded EEG and ECG in the laboratory. First, 14 of 1242 dogs dealt with over a 1 year period were chosen. They were trained for 2 h to lie quietly and to sleep in the laboratory; this training procedure was repeated 152 times. Three dogs were then selected and a permanent tracheostomy was performed in one. Finally, EEG and ECG were recorded with the bipolar fine needle electrodes; respiration was recorded simultaneously through a tube inserted to a tracheostomy in one dog. Wakefulness, slow wave sleep (SWS) and rapid eye movement (REM) sleep (REMS) were identified according to the EEG pattern and on the basis of the behavioral criteria. Recordings were performed 12 or 13 times in each dog. Complete sleep cycles, including wakefulness, SWS and REMS in this sequence, were observed 3.9-4.1 times. The mean duration of SWS was 2.2-4.4 min and that of REMS was 3.5-4.6 min. The REMS latency was 33.9-41.8 min. Fluctuation of heart rate with respiration, termed respiratory sinus arrhythmia, was noted in the ECG. Heart beat increased with inspiration and decreased with expiration. The present study demonstrates how to select and train sleeping dogs and shows their undisturbed daytime sleep and wakefulness patterns.

Animals↗
PubMed1983

Breathing during sleep: the responses to asphyxia and prochlorperazine in normal subjects and patients with obstructive sleep apnea.

The effects of sleep and prochlorperazine (12.5 mg intravenous bolus) on the ventilatory and arousal responses to asphyxia were studied in normal subjects and patients with obstructive sleep apnea (OSA). The ventilatory response to asphyxia was reduced during non-rapid eye movement sleep in the six normal subjects studied (1.93 +/- 0.18 l min-1.% SaO2 awake vs. 1.01 +/- 0.10 l min-1.% SaO2 asleep; mean +/- SEM; p less than 0.01) (SaO2 = arterial oxygen saturation). In the two normal subjects studied during sleep following prochlorperazine administration, ventilatory responsiveness was increased (p less than 0.05) but arousal response to asphyxia was depressed (p less than 0.025). Although prochlorperazine increased waking ventilatory responsiveness to asphyxia in five of six patients with OSA (2.26 +/- 0.44 l min-1.% SaO2 vs. 4.77 +/- 1.39 l min-1.% SaO2; mean +/- SEM; p less than 0.01), the drug had no clinically significant effect on upper airway obstruction during sleep; in three patients, apnea frequency was slightly reduced but in four of six patients severity of hypoxemia during apnea was increased with drug administration. We conclude that prochlorperazine administration is unlikely to benefit patients with obstructive sleep apnea despite its ventilatory effects during wakefulness and sleep. This lack of effect may be explained by separate effects of the drug on ventilatory and arousal responses to asphyxia.

Adult↗
PubMed2006

Sleep disruption, daytime somnolence and 'sleep attacks' in Parkinson's disease: a clinical survey in PD patients and age-matched healthy volunteers.

Recent case reports of 'sleep attacks' (SA) in patients with Parkinson's disease (PD) generated concerns about drug-induced daytime somnolence in this population. However, there are nearly no comparative data on sleep and vigilance problems between PD patients and normal controls. We performed a cross-sectional survey in PD patients and age-matched controls using a structured questionnaire on PD history, treatments, co-morbidity, activities of daily living, habits, exercise, sleep pattern, driving, pre-existing nocturnal problems, daytime somnolence, episodes of SA and the circumstances in which such episodes occurred. Daytime somnolence was also measured with the Epworth Sleepiness Scale (ESS) and sleep quality with the Pittsburgh Sleep Quality Index (PSQI). 176 PD patients and 174 controls were included. The same proportion of PD patients (27%) and controls (32%) reported episodes of SA, but these were more frequent in PD patients and occurred more frequently during situations requiring attention (10.8% vs. 1.7%, p<10(-3)). More PD patients had abnormal daytime somnolence (ESS) and poor sleeping quality (PSQI). The most consistent factor associated with SA was the duration of levodopa therapy and the predictive value of an abnormal ESS score was rather poor (40.7%). Abnormal daytime somnolence and poor sleep quality at night are more frequent in PD patients than in normals. However, SA are reported in both groups, although less frequently in the normals during activities that requires attention.

Activities of Daily Living↗
PubMed2006

The link between cardiac autonomic activity and sleep delta power is altered in men with sleep apnea-hypopnea syndrome.

We hypothesize that sleep apnea-hypopnea alters interaction between cardiac vagal modulation and sleep delta EEG. Sleep apnea-hypopnea syndrome (SAHS) is related to cardiovascular complications in men. SAHS patients show higher sympathetic activity than normal subjects. In healthy men, non-rapid eye movement (NREM) sleep is associated with cardiac vagal influence, whereas rapid eye movement (REM) sleep is linked to cardiac sympathetic activity. Interaction between cardiac autonomic modulation and delta sleep EEG is not altered across a life span nor is the delay between appearances of modifications in both signals. Healthy controls, moderate SAHS, and severe SAHS patients were compared across the first three NREM-REM cycles. Spectral analysis was applied to ECG and EEG signals. High frequency (HF) and low frequency (LF) of heart rate variability (HRV), ratio of LF/HF, and normalized (nu) delta power were obtained. A coherency analysis between HF(nu) and delta was performed, as well as a correlation analysis between obstructive apnea index (AI) or hypopnea index (HI) and gain, coherence, or phase shift. HRV components were similar between groups. In each group, HF(nu) was larger during NREM, while LF(nu) predominated across REM and wake stages. Coherence and gain between HF(nu) and delta decreased from controls to severe SAHS patients. In SAHS patients, the delay between modifications in HF(nu) and delta did not differ from zero. AI and HI correlated negatively with coherence, while HI correlated negatively with gain only. Apneas-hypopneas affect the link between cardiac sympathetic and vagal modulation and delta EEG demonstrated by the loss of cardiac autonomic activity fluctuations across shifts in sleep stages. Obstructive apneas and hypopneas alter the interaction between both signals differently.

Adult↗