Analysis of complexity of EEG during sleep.

New multichannel descriptors of EEG activity: complexity (omega), total power (zeta) and generalized frequency (phi) were applied to whole night sleep analysis in 11 healthy subjects. The values of omega and phi decreased systematically from waking to slow wave sleep, and increased systematically in consecutive NREM-REM sleep cycles. The changes of zeta were opposite to omega and phi. These descriptors may be an alternative approach to the EEG sleep analysis.