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PubMed2006

Sex differences in sleep: the response to sleep deprivation and restraint stress in mice.

STUDY OBJECTIVES: Numerous clinical studies and sleep surveys have shown pronounced sex differences in the occurrence of insomnia and other sleep pathologies. It has been suggested that sex differences in sleep, while subtle under baseline conditions, may increase in magnitude under biological or environmental challenges. However, controlled and experimental studies on sleep under challenged conditions rarely include female subjects. In this context, we examined sex differences in sleep in the mouse, not only under baseline conditions, but also after sleep deprivation and restraint stress. DESIGN: Adult male and female C57BL/6J mice were implanted with electrodes to record sleep-wake architecture and sleep electroencephalogram under baseline conditions and after 6 hours of sleep deprivation or 1 hour of restraint stress at the beginning of the daily light phase. RESULTS: Although baseline sleep patterns slightly differed between the sexes, the homeostatic recovery response to sleep deprivation was similar. In contrast, the changes in sleep after restraint stress were markedly different between male and female mice, with males displaying a stronger initial suppression of sleep and a stronger rebound of rapid-eye-movement sleep later in the recovery phase. CONCLUSIONS: In mice, the fundamental homeostatic properties of sleep regulation may not differ between the sexes, but the way sleep is affected and disrupted by environmental influences may be sex dependent. The latter may reflect sex differences in stress sensitivity.

Animals↗
PubMed1990

Sleep stage physiology, mood, and vigilance responses to total sleep deprivation in healthy 80-year-olds and 20-year-olds.

Little is known about sleep and the effects of total sleep loss in the 'old old' (i.e., 80-year-olds). We investigated sleep, mood, and performance responses to acute sleep deprivation in healthy 80-year-olds (n = 10) and 20-year-olds (n = 14). The protocol consisted of three nights of baseline sleep, one night of total sleep deprivation, and two nights of recovery sleep. Mood and vigilance were tested using visual analog scales and a Mackworth clock procedure in the morning and evening of each study day. Daytime sleepiness was measured by five naps on the days following the third and sixth nights. Old subjects had lower sleep efficiency and less delta sleep than young subjects. However, sleep continuity and delta sleep were enhanced in both groups on the first recovery night, indicating that sleep changes in old subjects are at least partially reversible by this procedure. Surprisingly, young subjects had shorter daytime sleep latencies than the old, suggesting a greater unmet sleep need in the former group. Mood and performance were disturbed by sleep loss in both groups, but to a greater extent among the young. This suggests that acute total sleep loss is a more disruptive procedure for the young than for the old.

Adult↗
PubMed2005

Improved sleep continuity and increased slow wave sleep and REM latency during ziprasidone treatment: a randomized, controlled, crossover trial of 12 healthy male subjects.

OBJECTIVE: Ziprasidone, an atypical antipsychotic, is a potent dopamine (D(2)) and serotonin (5-HT(2A/C)) receptor blocker, has agonistic properties at the 5-HT(1A) receptor, and blocks serotonin and norepinephrine reuptake. These transmitter systems are closely related to the regulation of sleep. METHOD: The aim of this double-blind, placebo-controlled, randomized, crossover study was to investigate the effects of ziprasidone on polysomnographic sleep structure and subjective sleep quality. Twelve healthy male subjects were randomly assigned to receive ziprasidone 40 mg or placebo for 2 sessions each composed of 2 consecutive nights (night 1, standard sleep conditions; night 2, acoustic stress) 5 days apart. Treatment was administered orally 2 hours before bedtime. The study was conducted from April 2004 to July 2004. RESULTS: Ziprasidone significantly increased total sleep time, sleep efficiency, percentage of sleep stage 2, and slow wave sleep; decreased the number of awakenings; and significantly affected tonic and phasic REM sleep parameters, i.e., it decreased percentage of REM and REM density and profoundly increased REM latency. CONCLUSION: Ziprasidone's effects on the sleep profile are somehow opposite to what is known about sleep of depressed patients (e.g., disturbances of sleep continuity, a reduciton of slow wave sleep, and a disinhibition of REM sleep). Its REM sleep-suppressing properties resemble those of most, although not all, antidepressants and may be clinically relevant. The drug also demonstrates sleep-consolidating properties under both standard routine and acoustic stress conditions. These effects are most likely related to ziprasidone's 5-HT(2C) antagonism, 5-HT(1A) agonism, and serotonin and norepinephrine reuptake inhibition.

Acoustic Stimulation↗
PubMed1992

Effects of selective sleep deprivation on ventilation during recovery sleep in normal humans.

To assess the effects of selective sleep loss on ventilation during recovery sleep, we deprived 10 healthy young adult humans of rapid-eye-movement (REM) sleep for 48 h and compared ventilation measured during the recovery night with that measured during the baseline night. At a later date we repeated the study using awakenings during non-rapid-eye-movement (NREM) sleep at the same frequency as in REM sleep deprivation. Neither intervention produced significant changes in average minute ventilation during presleep wakefulness, NREM sleep, or the first REM sleep period. By contrast, both interventions resulted in an increased frequency of breaths, in which ventilation was reduced below the range for tonic REM sleep, and in an increased number of longer episodes, in which ventilation was reduced during the first REM sleep period on the recovery night. The changes after REM sleep deprivation were largely due to an increase in the duration of the REM sleep period with an increase in the total phasic activity and, to a lesser extent, to changes in the relationship between ventilatory components and phasic eye movements. The changes in ventilation after partial NREM sleep deprivation were associated with more pronounced changes in the relationship between specific ventilatory components and eye movement density, whereas no change was observed in the composition of the first REM sleep period. These findings demonstrate that sleep deprivation leads to changes in ventilation during subsequent REM sleep.

Adult↗
PubMed2006

The relationship between the rate of melatonin excretion and sleep consolidation for locomotive engineers in natural sleep settings.

BACKGROUND: The aim of the study was to examine the role that melatonin production plays in the regulation of sleep consolidation in a population of shiftworkers working and sleeping in their natural environments. METHODS: 253 locomotive engineers (249 male, 4 female, mean age = 39.7 years) participated in the study for a 2-week period whilst working their normal roster patterns. Participants recorded details for all sleep periods in a sleep diary and collected urine samples during each day's main sleep period. The samples were subsequently assayed for the metabolite of melatonin in urine, 6-sulphatoxymelatonin (aMT6s), and the rate of excretion during main sleep periods was calculated. RESULTS: Separate one-way factorial ANOVAs revealed a significant effect of time of sleep onset on aMT6s excretion rate, sleep duration, and subjective sleep quality. Generally, the rate of aMT6s excretion was lower, sleep duration was shorter, and sleep quality was lower for sleeps initiated during the daytime than for sleeps initiated at night. CONCLUSION: Combined with previous studies linking melatonin production and sleep propensity, and others demonstrating the relationship between sleep consolidation and melatonin production in forced desynchrony protocols, the current results indicate that low production of melatonin may play a role in the poor consolidation of daytime sleep in natural sleep settings.

Journal Article↗
PubMed2001

[Common causes of sleep disturbances in Icelandic children who undergo sleep studies.].

INTRODUCTION: Sleep disturbances are common problems in children. Frequently, these problems are attributed to learned behavioral patterns, but little is known about organic causes of sleep disturbances in children. Obstructive sleep apnea (OSA) is a common cause of sleep disordered breathing in adults. Gastroesophageal reflux (GER) is also common in this population. Less is known about OSA and GER as potential causative agents of sleep disturbances in children, and these medical problems have not been addressed in Icelandic children. This study was designed to investigate the organic causes of sleep disordered breathing in Icelandic children, evaluate their severity and possible therapies. MATERIAL AND METHODS: One hundred and ninty children who were referred to the Pediatric Department at Reykjavik Hospital due to sleep disturbances were hospitalized over night and a sleep study was recorded, using the sleep equipment, EMBLA. The latter machine has 16 channels that record informations about sleep patterns and breathing. The children were 0-18 years of age. Informations were collected from EEGs, EMGs, and eye movements to determine sleep stages, and with respiratory belts with sensors on the chest and abdomen as well as an air-flow sensor that measures airflow through the nose and mouth. When GER was suspected, a pH meter was inserted and the pH values were measured in the upper and lower parts of the esophagus. RESULTS: The results demonstrate that a large number of children who suffer from sleep disturbances have an underlying disease. Of 61 children who underwent a sleep study and were suspected to have OSA, 46 had a positive study that resulted in a change in therapy. In addition, 69 of 89 children who underwent pH measurements in the esophagus were diagnosed with GER which prompted changes in therapy. CONCLUSIONS: The study demonstrates that both OSA and GER are common problems in children with sleep disturbances. We conclude that sleep studies are important in the overall workup of children with sleep disturbances, and can provide valuable informations regarding the causes, prevalence and severity of these medical problems. Sleep studies also facilitate the selection of children who require specific treatments such as operation of the oropharynx or CPAP/BiPAP treatment for OSA, or drug therapy for GER.

English Abstract↗
PubMed2000

Continuous positive airways pressure for obstructive sleep apnoea.

BACKGROUND: Obstructive sleep apnoea (OSA) is the periodic reduction (hypopnoea) or cessation (apnoea) of breathing due to narrowing or occlusion of the upper airway during sleep. The mainstay of nocturnal treatment is continuous positive airway pressure (CPAP) therapy at home at night to prevent the resulting apnoea, hypoxia and sleep fragmentation which are believed to cause the symptoms of OSA. A number of clinical trials have evaluated the effectiveness of nasal CPAP) as a treatment. OBJECTIVES: The objective was to review the effects of CPAP in the treatment of obstructive sleep apnoea in adults. SEARCH STRATEGY: We searched Medline 1966 to 1996, Embase 1974 to 1996, Cinahl 1982 to 1995 and the reference lists of articles. We consulted experts in the field. SELECTION CRITERIA: Randomised trials comparing nocturnal CPAP with placebo or other treatments in adults with obstructive sleep apnoea and an apnoea/hypopnoea index greater than five per hour. DATA COLLECTION AND ANALYSIS: Trial quality was assessed and data were extracted independently by two reviewers. Study authors were contacted for missing information. MAIN RESULTS: Seven trials involving 177 people were included. All the studies had some methodological shortcomings. Six trials were of crossover design. Compared with placebo, CPAP showed significant improvements in several quality of life and depression measures. Patients preferred CPAP to placebo (odds ratio 0.4, 95% confidence interval 0.2 to 0.8). There was no significant effect on blood pressure or measures of sleepiness and sleep quality. Compared with oral appliances, CPAP significantly improved the apnoea/hypopnoea index (weighted mean difference -7.3, 95% confidence interval -10.0 to -4.7) and minimum oxygen saturation during sleep. Patients strongly preferred the oral appliance to CPAP (odds ratio 9.5, 95% confidence interval 4.3 to 21.1). REVIEWER'S CONCLUSIONS: CPAP appears to be more effective than placebo in improving some quality of life measures for people with obstructive sleep apnoea. It appears to be more effective than oral appliances in improving respiratory disturbances. People appear to prefer oral appliances over CPAP, but prefer CPAP over placebo.

Adult↗
PubMed2005

Gene expression in the rat brain during sleep deprivation and recovery sleep: an Affymetrix GeneChip study.

Previous studies have demonstrated that macromolecular synthesis in the brain is modulated in association with the occurrence of sleep and wakefulness. Similarly, the spectral composition of electroencephalographic activity that occurs during sleep is dependent on the duration of prior wakefulness. Since this homeostatic relationship between wake and sleep is highly conserved across mammalian species, genes that are truly involved in the electroencephalographic response to sleep deprivation might be expected to be conserved across mammalian species. Therefore, in the rat cerebral cortex, we have studied the effects of sleep deprivation on the expression of immediate early gene and heat shock protein mRNAs previously shown to be upregulated in the mouse brain in sleep deprivation and in recovery sleep after sleep deprivation. We find that the molecular response to sleep deprivation and recovery sleep in the brain is highly conserved between these two mammalian species, at least in terms of expression of immediate early gene and heat shock protein family members. Using Affymetrix Neurobiology U34 GeneChips , we also screened the rat cerebral cortex, basal forebrain, and hypothalamus for other genes whose expression may be modulated by sleep deprivation or recovery sleep. We find that the response of the basal forebrain to sleep deprivation is more similar to that of the cerebral cortex than to the hypothalamus. Together, these results suggest that sleep-dependent changes in gene expression in the cerebral cortex are similar across rodent species and therefore may underlie sleep history-dependent changes in sleep electroencephalographic activity.

Action Potentials↗
PubMedDate not supplied

[Impact of sleep hygiene on patients with obstructive sleep apnoea syndrome].

The purpose of this study was to evaluate the impact of a Sleep Hygiene brochure on a population of 36 patients recently diagnosed with Obstructive Sleep Apnoea Syndrome and beginning treatment. One expects that: 1) the information about Sleep Hygiene offered in the brochure would change some of the patients' habits toward sleep; and that, 2) this intervention in the form of a free informative brochure would have an echo in terms of a better subjective evaluation of sleep complaints. The sleep habits and the sleep complaints were evaluated in the pre-test. Those variables were re-evaluated in the post-test and at that time the patients filled in a scale of satisfaction with the information about Sleep Hygiene, in terms of its contribution to improving their sleep complaints. There were no significant differences in the level of compliance to Sleep Hygiene between the two periods, although the majority of the patients considered that Sleep Hygiene did improve their sleep difficulties. The low level of compliance may be due to the fact that patients already had reasonable Sleep Hygiene habits, and also to the fact that the scale was not sufficiently discriminative. In addition, the self-discipline that Sleep Hygiene involves may have collided with other demands such as the adaptation to treatment with CPAP (Continuous Positive Air Pressure). In a following study, it would be interesting to find if the levels of sleep hygiene compliance would change if they were implemented after the initial adaptation to CPAP, which would imply a longitudinal study. It would be helpful to keep reminding the patients of Sleep Hygiene importance, offering new and update brochures to the patients during consultations.

Adult↗
PubMed2004

A novel adaptive wrist actigraphy algorithm for sleep-wake assessment in sleep apnea patients.

STUDY OBJECTIVES: Current actigraphic algorithms are relatively less accurate in detecting sleep and wake in sleep apnea patients than in people without sleep apnea. In the current study, we attempted to validate a novel automatic algorithm, which was developed for actigraphic studies in normal subjects and patients with obstructive sleep apnea by comparing it on an epoch-by-epoch basis to standard polysomnography. DESIGN: Prospective cohort study. SETTING: Multicenter, university hospital, sleep laboratories. PARTICIPANTS: A total of 228 subjects from 3 different sleep centers (Skara, Boston, Haifa) participated. INTERVENTION AND MEASUREMENTS: Simultaneous recording of polysomnography and Watch_PAT100, an ambulatory device that contains a built-in actigraph. The automatic sleep/wake algorithm is based on both the quantification of motion (magnitude and duration) and the various periodic movement patterns, such as those occurring in patients with moderate to severe obstructive sleep apnea. RESULTS: The overall sensitivity and specificity to identify sleep was 89% and 69%, respectively. The agreement ranged from 86% in the normal subjects to 86%, 84%, and 80% in the patients with mild, moderate, and severe obstructive sleep apnea, respectively. There was a tight agreement between actigraphy and polysomnography in determining sleep efficiency (78.4 +/- 9.9 vs 78.8 +/- 13.4%), total sleep time (690 +/- 152 vs 690 +/- 154 epochs), and sleep latency (56.8 +/- 31.4 vs 43.3 +/- 45.4 epochs). While for most individuals the difference between the polysomnography and actigraphy was relatively small, for some there was a substantial disagreement. CONCLUSIONS: We conclude that this actigraphy algorithm provides a reasonably accurate estimation of sleep and wakefulness in normal subjects and patients with obstructive sleep apnea on an epoch-by-epoch basis. This simple method for assessment of total sleep time may provide a useful tool for the accurate quantification of obstructive sleep apnea in the home environment.

Adaptation, Physiological↗
PubMed2006

Sleep loss and REM sleep loss are hyperalgesic.

STUDY OBJECTIVES: Disturbed sleep is observed in association with acute and chronic pain, and some data suggest that disturbed and shortened sleep enhances pain. We report the first data showing, in healthy, pain-free, individuals, that modest reductions of sleep time and specific loss of rapid eye movement (REM) sleep produces hyperalgesia the following morning. DESIGN: Two repeated-measures design protocols were conducted: (1) a sleep-loss protocol with 8 hours time-in-bed, 4 hours time-in-bed, and 0 hours time-in-bed conditions and (2) a REM sleep-loss protocol with 8 hours time-in-bed, 2 hours time-in-bed, REM deprivation, and non-REM yoked-control conditions. SETTING: The studies were conducted in an academic hospital sleep laboratory. PARTICIPANTS: Healthy pain-free normal sleepers, 7 in the sleep-loss protocol and 6 in the REM sleep-loss protocol, participated. MEASUREMENTS: Finger-withdrawal latency to a radiant heat stimulus tested at 10:30 AM and 2:30 PM and the Multiple Sleep Latency Test conducted at 10:00 AM, noon, 2:00 PM, and 4:00 PM were measured. RESULTS: Finger-withdrawal latency was shortened by 25% after 4 hours of time in bed the previous night relative to 8 hours of time in bed (p < .05), and REM sleep deprivation relative to a non-REM yoked-control sleep-interruption condition shortened finger-withdrawal latency by 32% (p < .02). CONCLUSION: These studies showed that the loss of 4 hours of sleep and specific REM sleep loss are hyperalgesic the following day. These findings imply that pharmacologic treatments and clinical conditions that reduce sleep and REM sleep time may increase pain.

Acute Disease↗
PubMed2006

Sleep parameters in patients using pacemakers with sleep rate function on.

INTRODUCTION: The cardiovascular system (CVS) is heavily influenced by the autonomic nervous system. Additionally, there is a functional alteration during the various stages of sleep. In nonrapid eye movement (NREM), a state of cardiovascular relaxation occurs during stages three and four. A large amount of rapid ocular movements is concentrated in rapid eye movement (REM) sleep. During this phase, fluctuations in arterial pressure (AP) and heart rate (HR) can be readily noted. Sleep disordered breathing (SDB) has been associated with cardiac rhythm disorders. Recently, cardiac rhythm disorder treatment with pacemaker (PM) highlighted a reduction in abnormal respiratory events during sleep. OBJECTIVE: Comparison of sleep parameters of patients using PM with a sleep rate (SR) algorithm based on its rate-modulated capability during physical activity (Integrity PM with SR function on and off). METHODS: Twenty-two patients (14 women, 8 men), implanted with an Integrity PM (St. Jude Medical Cardiac Rhythm Management Division, Sylmar, CA) with SR function for standard clinical indications, were evaluated utilizing a double-blind protocol. The indication for pacing included sinus node disease (SND), atrium ventricular blockage (AVB), and atrial fibrillation (AF). Following randomization, half of our patients had SR function switched to "on" mode while the other half were on "off" mode. During the first stage of the protocol, all patients underwent two consecutive nights of polysomnographic sleep recordings (PSG). During the first night patients slept in the sleep lab only for adaptation purpose. PSG full recording was carried out in the subsequent night. At a later stage, the programing of SR functions was shifted to "on" or "off" modes. One week later, a third assessment was undertaken. RESULTS: Twelve patients (54%) showed sleep efficiency improvement (total sleeping time/recording time) with PM SR on. This group had the least effective sleep efficiency with PM off, if compared with the others who highlighted no change in this sleep parameter (72 +/- 12 vs 81 +/- 7%, P = 0.01, respectively). This first group displayed a lower latency for REM sleep than the last one (89 +/- 55 vs 174 +/- 107 minutes, P = 0.01, respectively). In 11 (50%) patients, the number per sleep hour of microarousals was reduced when PM SR was switched on. When we compared such findings to the group whose parameters had not changed, we noted that the first set of patients were sleepier (ESE: 9 +/- 4 vs 5 +/- 5, P = 0.04, respectively), and showed more microarousals with PM SR off (20 +/- 14 vs 7 +/- 5 microarousal/hour, P = 0.007). CONCLUSION: In PM patients with sleep-related issues, the SR function activation improved sleep both from a qualitative and quantitative perspective.

Aged↗
PubMed1985

Apnea duration and hypoxemia during REM sleep in patients with obstructive sleep apnea.

Nocturnal sleep studies of 12 patients with obstructive sleep apnea and a matched control group of 12 subjects without the sleep apnea syndrome were analyzed to compare arterial oxyhemoglobin saturation (SaO2) during REM and non-REM sleep. Mean percentage of total sleep time spent in REM sleep was not significantly different in patients with obstructive sleep apnea and in subjects without significant apnea (14.2 +/- SEM 2.2 percent in patients vs 12.0 +/- 2.2 percent in nonapnea subjects). Apneas were longer during REM than non-REM sleep in all 12 patients (p less than 0.01). Oxyhemoglobin desaturations were more frequent during REM than non-REM sleep in both apnea patients and the control subjects. In addition, there was a greater mean fall in SaO2 per desaturation episode in both the apnea patients and non-apnea subjects. We conclude: 1) sleep apneas are longer during REM sleep than non-REM sleep in patients with obstructive sleep apnea; 2) hypoxemia is greater during REM sleep than non-REM sleep in subjects with and without the sleep apnea syndrome.

Adult↗
PubMed2002

Relationship of epileptic seizures to sleep stage and sleep depth.

STUDY OBJECTIVES: Interictal epileptiform discharges (IEDs) are facilitated by NREM stages 3 and 4 sleep and as sleep is deepening. To determine whether sleep influences seizures in a similar way to IEDs, we examined seizure rates in various stages of sleep in epilepsy patients undergoing overnight video-EEG-polysomnography (VPSG). DESIGN: Cross-sectional study. SETTING: Neurology Department. PATIENTS, MEASUREMENTS, AND INTERVENTIONS: We reviewed VPSGs from our Sleep and Epilepsy Laboratories to identify patients with recorded seizures during sleep. A total of 55 patients having 117 seizures were identified. RESULTS: Ninety-five percent of seizures occurred in NREM sleep (61% in stage 2, 20% in stage 1, 14% in stages 3 and 4 combined), and 5% in REM sleep. Adjusting for time spent in each stage of sleep, patients had 0.34 seizures per hour in stage 1, 0.38 seizures per hour in stage 2, 0.29 seizures/hr in stage 3 and 4 combined, and 0.09 seizures per hour in REM sleep. Seizures/hour was higher in NREM sleep (0.35 for NREM and 0.09 for REM; p=0.0001). For single seizures occurring in 1 night, seizure rate was significantly higher in NREM stages 1 and 2 as compared to NREM stages 3 and 4 sleep. A significant increase in log delta power, an automated measure of sleep depth, was observed in the 10 minutes prior to seizures. CONCLUSIONS: Both seizures and IEDs are facilitated by NREM sleep. While deeper stages of NREM sleep activate IEDs, lighter stages of NREM sleep promote seizures, at least for single seizures occurring in 1 night.

Adolescent↗
PubMed1996

Objective assessment of sleep and alertness in medical house staff and the impact of protected time for sleep.

We studied 26 physicians in postgraduate medical training ("house staff") to objectively quantify their sleep, alertness, and psychomotor performance while working on call. This study provided precise data on the extent of sleep deprivation during a typical call night, the workload factors predictive of sleep loss, and the extent to which protected time for sleep within the call night can ameliorate sleep loss and consequent daytime sleepiness. We used ambulatory EEG recording equipment and a standardized computer-based performance test to monitor sleep and alertness over the course of a 36-hour call day. Comparisons were made between interns provided with 4 hours of protected time for sleep by a covering resident ("night-float") and interns without such coverage. As anticipated, we found evidence that hospital interns were severely sleep-deprived, to an extent even greater than prior behavioral observations have suggested. Interns in both conditions spent an average of less than 5 hours (295.4 minutes) in bed attempting to sleep and obtained an average of 3.67 hours (220.1 minutes) of sleep (range 37.4-358.4 minutes). Provision of the night-float for 4 hours did not significantly change total sleep time (TST) (212.8 minutes covered vs. 224.9 minutes uncovered), but sleep efficiency was significantly improved (86.5% vs. 70.3%; p = 0.001). Covered interns also obtained significantly more slow-wave sleep than the uncovered interns (65.4 minutes vs. 51.1 minutes; p = 0.05). However, measures of alertness and performance were not significantly different between the two groups and were only weakly related to TST. These data suggest that significant chronic sleep deprivation is relatively unaffected by sleep obtained in the hospital and that provision of protected time for sleep does not significantly improve TST.

Adult↗
PubMed1998

Sleep architecture in a canine model of obstructive sleep apnea.

Obstructive sleep apnea (OSA) causes recurrent sleep disruption that is thought to contribute to excessive daytime sleepiness in patients with this disorder. The purpose of this study was to determine the specific effects of OSA on overall sleep architecture in a canine model of OSA. The advantage of this model is that sleep during long-term OSA can be compared to both normal sleep before OSA and recovery sleep after OSA. Studies were performed in four dogs in which sleep-wake state was monitored continuously by a computer that received telemetered EEG and EMG signals. Whenever sleep was detected, the computer sent a signal to close a valve through which the dog breathed; when the dog awoke the occlusion was released. In each dog, data were analyzed from 4 consecutive nights in three phases: a control phase before induction of OSA, a phase during long-term OSA (mean = 85 days, apnea index = 59/hour), and a recovery phase after cessation of OSA. During recovery there was a significant increase in the amount of rapid-eye-movement (REM) sleep compared to the OSA phase (p < 0.01), as well as significant increases in sleep efficiency and decreases in wakefulness (p < 0.01), similar to that reported in OSA patients. The REM rebound during recovery, however, could not be attributed to overall REM deprivation since the amount of REM sleep during the OSA phase was not different from the control phase (p = 0.708). This finding suggests that REM rebound during recovery from OSA is not the result of an overall REM sleep deficit per se. Rather, repeated sleep disruption due to the effects of repetitive apneas and hypoxia may lead to an increased REM sleep drive that manifests itself as a REM sleep rebound during recovery sleep after OSA.

Animals↗