The effects of evening bright-light on human body temperature and sleep architecture

摘要: A number of influential theories sleep function argue for a close relationship between body temperature and architecture. The energy conservation theory thermoregulatory sleep, including the central nervous system restoration protection theories, each predict increased Slow Wave Sleep (SWS) following elevations in at onset and during sleep. It has recently become apparent that appropriately timed evening bright-light (BL) (>2500 lux) may suppress melatonin, elevate core temperature, and produce delays human Core Temperature Rhythm (CTR). While these effects are being investigated their potential within industry to treat various affective related disorders, effects evening BL on sleep are unclear as literature is small differing results reported. effects of suggest enhanced SWS might follow BL, as increased been empirically associated with at sleep and, lesser extent, phase-delay CTR. However, the suppression melatonin suggests be disrupted, proposed be hypnotic agent. In present thesis three experiments reported which were designed to investigate rectal In the first experiment 11 male subjects twice exposed or Dim-Light (DL) (normal room illumination) 2hrs prior habitual bedtime two consecutive nights crossover design. Rectal was significantly elevated during first second hours more Stage 3 sleep occurred trend fourth cycle. The designed assess immediate of evening independent from CTR phase-shifting produced after multiple exposures consecutive evenings. run conditions. BL condition Ss evenings DL the fourth. dim-light condition all four It was anticipated would phasedelay the CTR such rhythm delay sleep could assessed itself night 4. On 1 no significant elevation found but fourth sleep cycle. 3 elevated during Slow Wave Activity (SWA) (.25-3 Hz EEG activity) across night, most noticeably in the third No differences position evident on night 4, lower than the DL fifth light exposure. In addition, latency (SOL) amounts Wake the BL this night. indicated administered until habitual over nights on core without necessarily delaying enhancing effects when, only was significantly around time onset. This also suggested these robustly one exposure BL. The test hypothesis. betweensubjects design utilised groups 12 run in Dim-Dim (DD) to DL nights. Dim-Bright (DB) were exposed 2 the Bright-Bright (BB) both nights. Rectal hour treatment BB non-significantly the , DB compared DD condition. SWA Total Power (TP) (0.25 Hz 50 addition, occur cycle conditions Thus, evening upon single exposure, by exposure the previous night. Taken together indicate bright light elevates SWS/SWA increases subsequent sleep, particularly late These consistent other experimental paradigms raised (e.g. exercise passive heating) and SWS observed increase. Interpreted way add of evidence thermoregulation intimately linked. Another possible interpretation rebound early suppression by bright-light later same also possible that thermal evening bright-light; maintained levels under of melatonin suppression period while resulted prominent SWS. Further research examine possibility monitoring plasma levels, temperature continuously bright-light. major finding until bedtime produces SWS/SWA, especially