CIRCADIAN TEMPERATURE AND CORTISOL RHYTHMS DURING A CONSTANT ROUTINE ARE PHASE-DELAYED IN HYPERSOMNIC WINTER DEPRESSION

Circadian temperature, cortisol, and thyroid-stimulating hormone (TSH) rhythms during a constant routine were assessed in 6 female controls and female patients with hypersomnic winter depression (seasonal affec tive disorder, SAD) before and after morning bright light treatment. A fter sleep was standardized for 6 clays, the subjects were sleep-depri ved and at bed rest for 27 hours while rectal temperature, cortisol, a dn TSH levels were assessed. The minimum of the fitted rectal temperat ure rhythm was phase-delayed in the SAD group compared to the controls 5:42 AM vs. 3:16 AM (p <.005); with bright light treatment, the minim um advanced from 5:42 AM to 3:36 AM (p=.06). The minimum of the cortis ol rhythm was phase-delayed in the SAD group compared to the control g roup, 12:11 AM vs. 11:03 PM (p <.05); with bright light treatment, the minimum advanced from 12:11 AM to 11:38 PM (P =.06). The acrophase of the TSH rhythm was not significantly phase-delayed in SAD subjects co mpared to control, though the trend appeared to be toward a phase-dela y (p=.07). After bright light therapy, the TSH acrophase was not signi ficantly different in the SAD subjects; the trend was a phase-advance (p=.09). Overall, the data suggest that circadian rhythms are phase-de layed relative to sleep in SAD patients and that morning bright light phase-advances those rhythms. (C) 1997 Society of Biological Psychiatr y.