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Internal deliberations (focused thoughts) and endogenous percepts (hallucinations) vary in a reciprocal manner across the states of waking and sleep, paralleling changes in regional brain activation. As subjects go from waking through sleep onset to NREM sleep and then to REM sleep, they report progressively more hallucinoid imagery and progressively less thinking. We have investigated whether this reciprocity in cognition between NREM and REM is maintained throughout the night. To do so, we analyzed 229 REM and 165 NREM reports collected with the Nightcap sleep monitoring system from 16 participants in their homes over 14 nights. The reports were scored for the presence of hallucinations and directed thinking by external judges. As predicted, hallucinations were more frequent in REM than in NREM for each segment of the night, and directed thinking was more frequent in NREM in the first 5 h of the night. Late in the night, directed thinking was equally infrequent in NREM and REM. At the same time, hallucinations increased within both NREM and REM as the night progressed, whereas directed thinking decreased in NREM and remained at a stable, low level in REM. These findings suggest that a reciprocal shift in focused thinking and hallucinating is a general property of cognitive activity across the wake–sleep cycle. Biological evidence supports the hypothesis that these cognitive changes are governed by specific state regulatory and neurocognitive processes at several levels of the brain. [ABSTRACT FROM AUTHOR]

A precipitous decline in eyelid movements (ELMs) has been shown to be a highly reliable indicator of sleep onset. While ELMs correlate well with eye movements during waking and rapid eye movement (REM) sleep, the eye sensor remains silent during the period of slow eye movements (SEMs) typical of sleep onset. If the ELM density (e.g. ELMs per minute) dropped simultaneously with the appearance of SEMs prior to sleep onset, it could be a promising tool for identifying decreases in alertness prior to overt sleep onset. The present study was designed to determine whether the presence of SEMs in the transitional period preceding stage 1 sleep is reflected in decreases in ELM density. ELM densities were computed for 2.5-s epochs with and without SEMs, as well as for 15-s epochs. Decreases in ELM density not only were an excellent correlate of the appearance of SEMs during wakefulness with closed eyes, but also a good predictor of their occurrence ( c. 82% accuracy) at a time resolution of 2.5 s. Based on these results, we conclude that ELM density reliably predicts moderate changes in the level of alertness during quiet wakefulness. [ABSTRACT FROM AUTHOR]

Clinical lore and a small number of published studies report that the selective serotonin reuptake inhibitors (SSRIs) intensify dreaming. This study examines the dream effects of paroxetine and fluvoxamine in order to both increase clinical knowledge of these agents and to test an important potential method for probing the relationship between REM sleep neurobiology and dreaming in humans. Fourteen normal, paid volunteers (4 males, 10 females; mean age 27.4 year, range 22–39) free of medical or neuropsychiatric symptoms as well as of psychotropic or sleep affecting drugs completed a 31-day home-based study consisting of: 7 days drug-free baseline; 19 days on either 100 mg fluvoxamine (7 Ss) or 20 mg paroxetine (7 Ss) in divided morning and evening doses; and 5 days acute discontinuation. Upon awakening, subjects wrote dream reports, self-scored specific emotions in their reports and rated seven general dream characteristics using 5-point Likert scales. Dream reports were independently scored for bizarreness, movement and number of visual nouns by three judges. REM sleep-related measures were obtained using the Nightcap ambulatory sleep monitor. Mean dream recall frequency decreased during treatment compared with baseline. Dream report length and judge-rated bizarreness were greater during acute discontinuation compared with both baseline and treatment and this effect was a result of the fluvoxamine-treated subjects. The subjective intensity of dreaming increased during both treatment and acute discontinuation compared with baseline. Propensity to enter REM sleep was decreased during treatment compared with baseline and acute discontinuation and the intensity of REM sleep increased during acute discontinuation compared with baseline and treatment. The decrease in dream frequency during SSRI treatment may reflect serotonergic REM suppression while the augmented report length and bizarreness during acute SSRI discontinuation may reflect cholinergic rebound from serotonergic suppression. [ABSTRACT FROM AUTHOR]

Microarousals (MAs) are brief transient events that occur during normal sleep in humans and with increased frequency in disordered sleep, especially in association with sleep apnoea. In a feline model, we discovered transient cardiorespiratory events during nonrapid eye movement (NREM) sleep that exhibited consistent features with similarities to human MAs. It was observed that MAs have two distinct phases. Phase I (MAI) is characterized by an abrupt increase in electromyogram (EMG) amplitude (> 50%), increased electrooculogram (EOG) activity and accelerated frequency of hippocampal electroencephalographic (EEG) activity. MAI lasts 4.1 ± 0.3 s. Phase II (MAII), lasting 9.8 ± 0.8 s, is characterized by high frequency EEG activity, but EMG, EOG and hippocampal activity remain at baseline levels. Mean inspiratory rate begins to increase 15 s before the onset of the MA, followed 10 s later by the increase in mean heart rate. Mean respiratory rate decreases sharply through MAII, and returns to baseline levels 15 s after the MA. During MAII mean heart rate decreases quickly; there is increased respiratory irregularity, followed by a prolonged ventilatory overshoot. The abrupt shift in heart rate is coincident with the change in breath timing seen during MAII. Heart rate returns to baseline levels 10 s following the MA. Integrating our findings with those described previously in humans, we propose that MAs may serve as a homeostatic mechanism which is designed to restore cardiorespiratory function allowing the continuity of sleep. [ABSTRACT FROM AUTHOR]

Summary This study presents new findings of carbachol-induced long-term ponto-geniculo-occipital (PGO) enhancement lasting five days, but without REM sleep enhancement. A quantitative analysis of the number and types of bilateral PGO wave events during slow wave sleep with PGO activity (SP) and REM was performed in each of four cats over a period of six days following a single unilateral microinjection of carbachol nanospheres into the caudolateral peribrachial area. The results demonstrate increases in the summed total of all PGO wave events to continue for five days postcarbachol reaching a peak sixfold increase on day three in SP and REM. The tendency of PGO waves to occur in clusters of greater than three waves increased sevenfold on day three in SP and fourfold during REM. These findings indicate a dissociation of long-term PGO enhancement from long-term REM enhancement, and suggest that even a sixfold increase in PGO activity alone is not, in itself, sufficient to produce the cholinergic orchestration of REM sleep enhancement. [ABSTRACT FROM AUTHOR]

In this paper, we describe the first field tests of a home-based sleep monitoring system, the Nightcap, which uses eyelid and body movement sensors to discriminate wake, NREM, and REM sleep automatically. Ten normal young adults were studied in the sleep laboratory and at home to allow comparison of Nightcap-derived measures with those obtained by traditional polysomnography. The agreement between the two techniques was 87% based on I-min epochs-93% for NREM, 80% for REM, and 72% for wake. When the values for sleep latency, REM latency, wake time, NREM time, and REM time calculated from polysomnograph records were compared with the values calculated from Nightcap data, no significant differences were seen. In cases of extremely poor sleep, objective sleep efficiency estimates correlated well with subjective reports, suggesting that the Nightcap is sensitive to clinically relevant changes in the quality of sleep. This new device should prove useful to researchers wishing to study the psychophysiology and pathophysiology of sleep in more naturalistic and cost-effective paradigms than possible in the traditional sleep laboratory. [ABSTRACT FROM AUTHOR]

The purpose of this study was to develop an inexpensive, simplified home monitoring system for prescreening certain sleep complaints and for long-term home-based experiments. Four subjects slept in the laboratory for 3-4 nights. In addition to a standard polysomnogram, piezoelectric ceramic transducers were attached to both hands, both feet, and over the right eyelid. The sleep from 2 nights of each subject was staged according to the standard criteria. The limb transducers identified major and minor body shifts and were used to signal possible state changes. The data from the eye movement sensor was used to develop a REM-state algorithm. Using this algorithm, REM and NREM sleep were identified with 92% (SD=0.091) and 91% (SD=0.076) accuracy, respectively. The ultimate goal is to have a bedside device programmed with the algorithm that would either store information or score the data on-line for waking, NREM, and REM states. We conclude that a system monitoring eye movements and major body shifts is a promising approach to an economical and accurate home recording system. [ABSTRACT FROM AUTHOR]

Although 20% of myocardial infarctions (MIs) and 15% of sudden cardiac deaths (SCD) occur between midnight and 6:00 A.M., nocturnal cardiac death remains an underappreciated and poorly understood phenomenon. The risk of nocturnal SCD may be-especially high in patients with coronary disease confounded by apnea, heart failure, recent Ml, pause-dependent Torsade de Pointes, and near miss victims of sudden infant death syndrome (SIDS) or siblings of SIDS vistims. During rapid eye movement (REM) sleep and dreaming, significant bursts in sympathetic nervous system activity may compromise coronary flow and trigger life-threatening arrhythmia in susceptible individuals. In non-REM or slow wave sleep, hypotension may lead to malperfusion of the heart and brain as a result of a lowered pressure gradient through stenosed vessels. Obstructive sleep apnea, which afflicts 1.5 million Americans, can generate reductions in arterial oxygen saturation, which may lead to hypertension and greatly increased risk of myocardial infarction. Cardiac medications which cross the blood-brain barrier have the potential to alter sleep structure and provoke nightmares with severe cardiac autonomic discharge. Recently, new streamlined technology has been developed for tracking of sleep state. Among the most promising is the Nightcap, an unobtrusive, low cost device which accurately detects sleep state from eyelid and head movement with algorithms which could be incorporated into the circuity of ambulatory ECG recorders. Sleep states present unique autonomic, hemodynamic, and respiratory challenges to the diseased myocardium which cannot be replicated by daytime diagnostic tests. Because of the magnitude of the problem of nocturnal death and the availability of new practical technology for combined monitoring of sleep state and ECG, more widespread nighttime monitoring of the cardiac patient seems warranted. [ABSTRACT FROM AUTHOR]

Presents the abstracts of papers presented to the 9th Annual Meeting of the Association for the Psychophysiological Study of Sleep, held in Boston, Massachusetts on March 20-23, 1969. Psychological correlates of phasic and tonic events during sleep; Phasic events and mentation during sleep; Dream content and physiological functioning; Time-related changes in physiological characteristics of rapid eye movement.