Slow-wave sleep

About: Slow-wave sleep is a research topic. Over the lifetime, 6543 publications have been published within this topic receiving 320663 citations. The topic is also known as: deep sleep.

Dynamics of the sleep EEG after an early evening nap: experimental data and simulations

Abstract: Increasing sleep pressure is associated with highly predictable changes in the dynamics of the sleep electroencephalogram (EEG). To investigate whether the effects of reduced sleep pressure also can be accounted for by homeostatic mechanisms, nighttime sleep following an evening nap was recorded in healthy young men. In comparison with the baseline night, sleep latency in the postnap night was prolonged, rapid eye movement sleep (REMS) latency was reduced, and EEG power density in non-REMS was decreased in the delta and theta band. The buildup of both EEG slow-wave activity (SWA; power density in the 0.75-to 4.5-Hz range) and spindle frequency activity (SFA; power density in the 12.25-to 15.0-Hz range) in non-REMS episodes was diminished (SWA: episodes 1-3; SFA: episode 1). The typical declining trend of SWA over consecutive non-REM sleep episodes was attenuated. The time course of SWA could be closely simulated with a homeostatic model of sleep regulation, although some discrepancies in level and buildup of SWA were apparent. We conclude that homeostatic mechanisms can largely account for the dynamics of the sleep EEG under conditions of reduced sleep pressure.

Monitoring and Staging Human Sleep

Abstract: Polysomnography involves recording a wide assortment of bioparameters while an individual sleeps. Knowledge of the fundamental principles of electrode application, equipment calibration, and recording technology is essential for high-quality data collection. The findings from the electroencephalogram (EEG), electrooculogram, and electromyogram (EMG) can be summarized according to specific scoring criteria as sleep stages N1, N2, N3, and R (previously called stage 1, 2, 3, 4, and REM). Scoring criteria depend on EEG bandwidth activity (delta, theta, alpha, and beta), EEG events (vertex sharp waves, sleep spindles, and K-complexes), eye movement activity (slow and rapid eye movements), and the level of muscle tone. Stage N1 is characterized by a low-voltage, mixed frequency background EEG, as well as EMG similar to relaxed wakefulness, and may include slow rolling eye movements and vertex sharp waves. Stage N2 is characterized by the presence of sleep spindles and K-complexes, combined with a low-voltage, mixed frequency background. Stage N3 is characterized by high-voltage slow-wave activity present for at least 20% of the epoch. Stage R (or REM) sleep is scored when rapid eye movements and low skeletal muscle tone accompany a low-voltage, mixed frequency background EEG. Central nervous system (CNS) arousals also may occur from sleep, either spontaneously or resulting from pathophysiologies or environmental stimuli (e.g., noise or touch). Quantitative analysis of sleep stages and CNS arousals provide evidence for, contribute to the definition of, and index severity of some sleep disorders. Similarly, these measures can provide objective outcome measures for assessing therapeutic interventions. This article summarizes recording, digital processing, and scoring techniques used for evaluating brain activity during human sleep and its disturbance by CNS arousals.