Diurnal variations in REM and NREM sleep EEG power spectra in the rat

Diurnal variations were observed in the EEG power spectra of REM sleep and non-REM (NREM) sleep in the rat. Diurnal variations occurred in peak EEG frequency and spectral power (0-27 Hz and 5-9 Hz bands) during REM sleep. During NREM sleep diurnal variations were observed in spectral power in the 0-27 Hz and 0-4 Hz bands. The significance of these findings is discussed in terms of correlative data involving diurnal variations in neurotransmitters and hormones, all of which have been implicated in the induction or maintenance of sleep states.