High-frequency components of the rat electrocorticogram are modulated by the vigilance states.

In view of the reports that in the human magnetoencephalogram, 40-Hz oscillations are more abundant in waking and REM sleep than in non-REM sleep, we performed a 24-h broad-band (0.25-64 Hz) spectral analysis of the electrocorticogram in unrestrained rats. Spectral power above 33 Hz was higher in waking and REM sleep than in non-REM sleep, and in the range of 6-38 Hz it was higher in REM sleep than in waking.

Effects of melatonin and the melatonin receptor agonist S-20098 on the vigilance states, EEG spectra, and cortical temperature in the rat.

The effects of melatonin (3 mg/kg i.p.) and the melatonin receptor agonist S-20098 (3 mg/kg i.

Sleep deprivation in the rat at different ambient temperatures: effect on sleep, EEG spectra and brain temperature.

To investigate the relationship between thermoregulation and sleep regulation, rats were sleep-deprived for 3 hours at two different ambient temperatures. Sleep deprivations (SD) were performed at 23 degrees C (SD-23) and at 32 degrees C (SD-32) in the beginning of the 12-h light period in animals chronically implanted with ECoG and EMG electrodes, and with epidural and hypothalamic thermistors. SD-32 enhanced cerebral temperature more than SD-23 at both brain sites.

Simulation of daytime vigilance by the additive interaction of a homeostatic and a circadian process.

The two-process model of sleep regulation postulates that a homeostatic and a circadian process underlie sleep regulation. The timing of sleep and waking is accounted for by the interaction of these two processes. The assumptions of two separate processes or of a single process resulting from their additive interaction are mathematically equivalent but conceptually different.

Effects of 12-h sleep deprivation and of 12-h cold exposure on sleep regulation and cortical temperature in the rat.

The predictions of the two-process model of sleep regulation were tested by 12-h sleep deprivation (SDEP) and 12-h cold exposure (cold, 4 degrees C) in the rat, both carried out in the 12-h dark period. The analysis was based on recordings of vigilance states, electroencephalogram (EEG) power spectra (0.25-25.

[Pharmacotherapy of sleep disorders].

Benzodiazepines and related drugs are the hypnotics of first choice. They shorten sleep latency, enhance sleep continuity and may prolong sleep duration. Their undesired effects include a persistent day-time sedation and ataxia when getting up at night.

Period-amplitude analysis and power spectral analysis: a comparison based on all-night sleep EEG recordings.

Both period-amplitude analysis (PAA) and power spectral analysis (PSA) were performed on all-night human sleep EEG recordings obtained from 11 subjects. The comparison of the two methods was based on the PAA variables time in band (a wave incidence measure) and rectified amplitude, and on the PSA variables spectral power density and spectral amplitude (the square root of power). The mean time course of these variables was determined for the first 4 nonREM-REM sleep cycles.

All-night dynamics of the human sleep EEG.

The dynamics of the sleep EEG were investigated by all-night spectral analysis of 51 sleep records. Power density was calculated for 1-Hz bins in the 0.25-25.

Repeated partial sleep deprivation progressively changes in EEG during sleep and wakefulness.

The effect of repeated partial sleep deprivation on sleep stages and electroencephalogram (EEG) power spectra during sleep and wakefulness was investigated in nine healthy young subjects. Three baseline nights of 8 hours (2300-0700 hours) were followed by four nights with 4 hours of sleep (2300-0300 hours) and three recovery nights of 8 hours (2300-0700 hours). Sleep restriction curtailed sleep stages 1 and 2 as well as rapid eye movement (REM) sleep, but left slow wave sleep largely unaffected.

A model of human sleep homeostasis based on EEG slow-wave activity: quantitative comparison of data and simulations.

EEG slow-wave activity (SWA; spectral power in the 0.75-4.5 Hz band) is a function of the duration of prior waking and, thereby, an indicator of sleep homeostasis.

European isolation and confinement study. Twenty-four hour rhythm of rest/activity and sleep/wakefulness: comparison of subjective and objective measures.

The purpose of this study in the ISEMSI project was to record continuously the rest-activity cycle of the six subjects by ambulatory monitoring. It was planned to record the subjects during approximately 10 days of the pre-isolation period, the 28 days of isolation, and the 6-day post-isolation period. The three following major aims were envisaged: (1) to evaluate the possibility of monitoring the rest-activity cycle and sleep over prolonged time periods under conditions of confinement; (2) to examine the sleep period under the experimental condition in comparison to the pre- and post-experimental periods; and (3) to compare objective and subjective measures of sleep.

The effects of ethanol on human sleep EEG power spectra differ from those of benzodiazepine receptor agonists.

A single dose of ethanol (0.60 g/kg of body weight) was administered to eight young healthy male subjects 35 minutes before bedtime. Compared to the average value of two baseline nights, subjective sleep and polysomnographically determined sleep parameters were not significantly affected.

Dynamics of EEG slow-wave activity and core body temperature in human sleep after exposure to bright light.

In seven subjects sleep was recorded after a single 3-hour (2100-0000 hours) exposure to either bright light (BL, approx. 2,500 lux) or dim light (DL, approx. 6 lux) in a crossover design.

Combining different models of sleep regulation.

Different models have been proposed to account for processes underlying the regulation of sleep and alertness. Specific models have addressed sleep homeostasis, the nonREM-REM sleep cycle, the circadian sleep/wake rhythm, and changes of daytime alertness. We show that the different models are not mutually exclusive but that they can be integrated as 'modules' in a combined model.

Models of sleep regulation in mammals.

A brief overview of models on the regulation of sleep/waking or rest/activity is provided. Applications of the two-process model are illustrated in two species: The homeostatic facet of the model (Process S) was used to quantitatively simulate sleep in the rat and guinea pig. The model parameters were estimated for rat sleep by an optimization procedure.

Concepts and models of sleep regulation: an overview.

Various mathematical models have been proposed to account for circadian, ultradian and homeostatic aspects of sleep regulation. Most circadian models assume that multiple oscillators underlie the differences in period and entrainment properties of the sleep/wake cycle and other rhythms (e.g.

Cortical temperature and EEG slow-wave activity in the rat: analysis of vigilance state related changes.

Vigilance states, cortical temperature (TCRT), and electroencephalograph (EEG) slow-wave-activity (SWA, mean power density in the 0.75-4.0 Hz range) of ten rats were recorded continuously during a baseline day, and two recovery days (Recovery 1 and 2) after 24 h of sleep deprivation (SD).

Sleep and waking have a major effect on the 24-hr rhythm of cortical temperature in the rat.

The relationship between the time course of cortical temperature (TCRT) and sleep-wake alternation was investigated by correlation analyses and a computer simulation. The data for these analyses were collected in 10 rats in a 4-day experiment (LD 12:12), during which vigilance states and TCRT were determined for consecutive 8-sec epochs. On day 1 baseline recordings were obtained; on day 2 the animals were sleep-deprived; and days 3 and 4 served as recovery days.

Sleep homeostasis in the rat: simulation of the time course of EEG slow-wave activity.

According to the two-process model of sleep regulation, a homeostatic Process S increases during waking and declines during sleep. For humans, the time course of S has been derived from the changes in EEG slow-wave activity (SWA; spectral power density in the 0.75-4.

Sleep extension in humans: sleep stages, EEG power spectra and body temperature.

In eight male subjects the electroencephalogram (EEG) and core body temperature (Tcore) were recorded during long sleep episodes from 0000 to 1,500 hr. EEGs were visually scored and subjected to spectral analysis by fast Fourier transform. Slow-wave sleep [SWS, i.

Sleep deprivation in rats: effects on EEG power spectra, vigilance states, and cortical temperature.

Vigilance states, electroencephalogram (EEG) power spectra (0.25-25.0 Hz), and cortical temperature (TCRT) of 10 rats were obtained during a baseline day, a 24-h sleep deprivation (SD) period, and 2 days of recovery (recoveries 1 and 2).

Effects on night-time motor activity and performance in the morning after midazolam intake during the night.

The hypnotic action and residual effects of a single night-time dose of midazolam (Ro 21-3981, Dormicum, 7.5 mg; CAS 59467-70-8) were investigated in young, healthy adults. The subjects went to bed at the habitual time and were awakened 3 h later for drug or placebo intake.

Short light-dark cycles influence sleep stages and EEG power spectra in the rat.

To investigate the influence of light on sleep and the electroencephalogram (EEG), chronically implanted rats were continuously recorded during a baseline day under 12-h light-12-h dark (LD 12:12) conditions, and an experimental day with short LD (LD 1:1) cycles. The percentage of non-REM sleep (NREMS) was higher and the percentage of REM sleep (REMS) lower in the 1-h light [corrected] intervals than in the 1-h dark intervals. The maximum of NREMS induction by 1-h light occurred in the habitual 12-h dark period (activity period), while the largest enhancement of REMS by 1-h darkness occurred in the second half of the habitual 12-h light period (rest period).

Ultradian dynamics of sleep after a single dose of benzodiazepine hypnotics.

A single bedtime dose of the benzodiazepine hypnotics, flunitrazepam (2 mg), triazolam (0.5 mg) or flurazepam (30 mg), was administered to young, healthy subjects. Abortive first rapid eye movement sleep (REMS) episodes, characterized by a low level of EEG slow-wave activity (spectral power density in the 0.