Power spectral analysis of recovery sleep of sleep deprivation and hypnotic drug induced sleep

Hypnotic drugs induced sleep is usually different from physiological sleep in restoring body energy. The cause of the differences is not clear. To investigate the differences between these two types of sleep, in this study, hypnotic drug diazepam (DZP) induced sleep was compared with the recovery sleep following sleep deprivation. Power spectral analysis was used to reveal the different EEG features of these two types of sleep. EEGs were recorded in rat occipital cortex with implanted electrodes under three vigilance states of waking, slow wave sleep (SWS) and rapid eye movement (REM) sleep. Spectral powers of the EEG segments were evaluated in sub-bands of delta (0.5-4.0 Hz), theta (4.25-8.0 Hz), alpha (8.25-16.0 Hz), beta (16.25-25.0 Hz) and for total frequency range of 0.5-25.0 Hz. The data showed that both hypnotic drug DZP and sleep deprivation increased the time of SWS and REM sleep; however, DZP decreased low-frequency activity in SWS sleep, while sleep deprivation increased low-frequency activity in SWS sleep during recovery sleep. The decrease of low-frequency activity in DZP induced SWS sleep could result from the DZP inhibitory effects. The results suggest that increases of sleep evoked by different factors can have different features and the method of power spectral analysis is useful in revealing deep features of different types of sleep.