Reduced REM Latency in Depression: Mechanical Considerations-Reply

In Reply.—  We thank Dr Schwartz for his most interesting letter concerning our report.¹ As we stated there and in an earlier report on social zeitgebers and biologic rhythms,² our collaborative work on sleep physiology is embedded in an overall framework of biologic rhythms. We agree that the understanding of depression may very well require an increase in our knowledge base of several biologic rhythms, including sleep.Dr Schwartz suggests that we have confounded several key concepts, which may require some clarification.¹ In short, he has suggested that we have "mistakenly related increased REM pressure to decreased REM latency..." Perhaps there is a misunderstanding, since if one REM deprives individuals and REM latency shortens during the recovery sleep, a clear relationship exists between REM pressure and decreased REM latency.Dr Schwartz' second criticism is that we have "neglected the contributions of the desynchronization data and phase theories of mood