Altered phase relation between sleep timing and core body temperature rhythm in delayed sleep phase syndrome and non-24-hour sleep-wake syndrome in humans

Changes in the phase relation between sleep timi ng and the circadian pacem aker a re suspected to have an etiological significance in circadian rhythm sleep disorders. Simultaneous recordings of rest-activity and rectal tempe rature in seven sighted delayed sleep phase syndrome (DSPS) patients, seven sighted non-24-h sleep-wake syndrome (non-24) patients, and 14 healthy con trols were made for 10-14 days continuously in the subjects' homes. We foun d that sleep length a nd the interval from the body temperature (BT) trough to sleep offset were significantly longer in both non-24 and DSPS patients than in the controls, and that the interval between sleep onset and the BT trough was significantly less in the non-24 patients than in the DSPS pati ents and the controls. We postulate these alterations in phase relation to be associated with phase changes of the circadian pacemaker via different i llumination timings. (C) 2000 Elsevier Science Ireland Ltd. All rights rese rved.