Sleep onset REM episodes are associated with circadian parameters of body temperature. A study in depressed patients and normal controls.

Sleep and 24-hr body core temperature were measured during a 2- to 3-week study interval in 15 endogenous depressives, 12 patients after remission, and 10 normal control subjects. The total sample was subdivided into one group of persons who displayed at least one sleep onset REM episode (SOREM; latency less than or equal to 20 min) during the study interval and another group of persons who never had SOREMs; 14 persons (8 depressives, 3 remitted patients, and 3 control subjects) belong to the SOREM group, 23 persons (7 depressives, 9 remitted patients, and 7 control subjects) to the group without SOREMs. While the groups do not differ in the mean body core temperature, members of the SOREM group have a significantly smaller variation around the daily mean value. This is mainly due to a smaller difference between daytime and nighttime body temperature in the SOREM group. These data suggest that short REM latency is closely associated with alterations of body core temperature.