Abstract: It is explored whether there is correlation between the noise of the Electrocardiogram (ECG) and sleep stages.The distribution of the noise segments was statistically analyzed during wakefulness,light sleep,deep sleep,rapid eye movement (REM) sleep,and the transition periods between different sleep stages.Totally two sleep groups were selected from the cyclic alternating pattern (CAP) sleep database,including insomnia (<i<N</i<=7) and controls (<i<N</i<=14).Most noise segments were in wakefulness (insomnia 84.2%±16.0%,controls 53.6%±21.9%,<i<P</i<<0.01) and at the transition period between different sleep stages (insomnia 9.4%±12.7%,controls 23.6%±14.0%,<i<P</i<<0.05).ECG noise segments mainly distribute in wakefulness stages and secondly at the transition periods between different sleep stages.