Serotonin 1A Receptors, Melatonin, and the Proportional Control Thermostat in Patients With Winter Depression

In patients with seasonal affective disorder, light treatment lowers core temperature during sleep in proportion to its antidepressant efficacy. The regulation of the level of core temperature during sleep is linked with a proportional control thermostat in the central nervous system whose operation appears abnormal in patients with seasonal affective disorder. Because both melatonin and serotonin 1A receptor activation also lower core temperature, we investigated the relationship between (1) endogenous melatonin and core temperature profiles, (2) the proportional control thermostat, and (3) the core hypothermic response to the serotonin 1A receptor partial agonist ipsapirone hydrochloride in patients with seasonal affective disorder and healthy controls.