Sleep and circadian temperature rhythms in winter depression

Winter depression as associated with a phase-delay of the temperature rhythm in a constant routine is discussed. Bright morning light treats the depression and phase-advances the temperature rhythm. There is a need for a small inexpensive temperature monitoring device to diagnose and treat circadian rhythm problems. The preliminary data indicate that the circadian rhythm is abnormally timed in patients with winter depression relative to their sleep and that effective treatment with bright light in the morning tends to phase-advance their rhythm to a more normal time