Overnight human plasma melatonin, Cortisol, prolactin, TSH, under conditions of normal sleep, sleep deprivation, and sleep recovery

: Early investigations of the effect of sleep deprivation on plasma melatonin reported no major changes. Recently, 36 hrs of sleep deprivation was reported to elevate melatonin levels on the post‐sleep deprivation night. Given these contradictions melatonin, Cortisol, prolactin, and thyroid stimulating hormone before, during, and, after sleep deprivation were examined in nine healthy young males following one night of sleep deprivation. Hormone levels at hourly intervals, for each night, were statistically analyzed by a repeated measures, two‐way factorial ANOVA. ANOVA was also performed for measures of area under the curve (AUC). No significant differences were observed for melatonin levels. Cortisol was significantly higher on the sleep deprivation night presumably reflecting the aroused state accompanying being awake; however, there were several time points on the control night when it was elevated also. Prolactin was higher on the post‐sleep deprivation and control nights but did not rise on the deprivation night, indicating a useful nonpolysomnographic index for discriminating overnight sleep and awake states. TSH levels showed a similar rise during the control and sleep deprivation nights, but remained flat on the post‐sleep deprivation night. It appears that the pineal is insulated against feedback from changes to the level of arousal accompanying sleep and wakefulness. In comparison, Cortisol, prolactin, and TSH levels vary with these states and are, therefore, useful indices of arousal and sleep‐wake.