Abstract: Cyclic alternating pattern (CAP) during sleep is a kind of cyclic oscillation of EEG pattern in non-rapid eye movement sleep(NREM sleep), which reflects microstructure of sleep. It has been identified that CAP plays an important role in keeping the integrity of sleep. The purpose of the interview is to introduce the recording, identification, physiological meaning and clinic implication of CAP.

Key words: cyclic alternating pattern, polysomnography, sleep disorder