Sleep deprivation stimulates serotonin release in the suprachiasmatic nucleus

Recent literature suggests that sleep deprivation has a general stimulatory effect on the central serotonergic system. Herein we report that in hamste rs, sleep deprivation induced by gentle handling for 3 h under dim red ligh t at midday stimulates serotonin release in the suprachiasmatic nuclei by a s much as 171%. Basal levels of 5-HT release are re-established within I h after cessation of treatment. Sleep deprivation also evokes phase advances of the circadian activity rhythm averaging 2 h. When sleep deprivation is u ndertaken in bright tight, serotonin release is stimulated, but phase-shift ing is greatly inhibited. It is therefore proposed that if the phase-resett ing response to sleep deprivation is mediated by increased serotonin releas e, light inhibits the phase-resetting effect by blocking the postsynaptic o r other downstream actions of serotonin. NeuroReport 11:1929-1932 (C) 2000 Lippincott Williams & Wilkins.