Rapid Eye Movement Sleep Correlates with the Overall Activities of the Hypothalamic-Pituitary-Adrenal Axis and Sympathetic System in Healthy Humans

To assess the association of the overall amount of rapid eye movement (REM) sleep and the activities of the hypothalamic-pituitary-adrenal axis and sympathetic system, we performed polysomnography and measured 24-h urinary free cortisol and catecholamine excretion in 21 healthy adults. After an adaptation night, each subject was recorded in the sleep laboratory for 3 consecutive nights while 24-h urine specimens were collected. Urinary free cortisol, epinephrine, dihydroxyphenylglycol, and dihydroxyphenylacetic acid levels were significantly and positively correlated with the average values of percent REM sleep (P < 0.05). There were no correlations between hormone values and REM latency, other variables of REM distribution, or REM density, an index of phasic activity during REM sleep. The positive correlations between stress system activity and REM sleep are consistent with hormonal and sleep alterations in melancholic depression, a state characterized by increased cortisol and catecholamine secretion.