Early onset and accumulation of REM sleep in depression: a study of the phase-advance hypothesis

Twenty-two depressed subjects who met criteria for major depressive disorder were grouped according to their initial REM latency. Subjects with short (less than or equal to 60 min) initial REM latency were separated from those with normal (greater than 60 min) initial REM latency. Subjects with short initial REM latency were found to have earlier onsets to at least two subsequent REM periods. The number of minutes of REM sleep accumulated were also plotted against elapsed time after sleep onset. The short-latency group accumulated REM sleep earlier than, but at about the same rate as, the normal latency group. These data support the phase-advance hypothesis of REM sleep in depression.