Plasma Cortisol Levels in Depression

Sleep disturbance is commonly found in depression. Plasma cortisol levels in non-hospitalized normal subjects show a rise prior to waking, with peak values at between 5 and 8 a.m. (9, 10). In a group of eight normal subjects, Perkoff (10) changed the sleep rhythm to sleeping during the day, using darkened rooms, and found that the plasma cortisol level followed suit, rising sharply in the two-hour period before waking. He stated: “A fundamental characteristic of the diurnal variation of plasma 17 OHCS concentration is the abrupt rise which occurs during the sleep period.”