Background: It has been suggested that certain abnormalities (e.g., in phase or amplitude) of the circadian pacemaker underlie seasonal affective disorder.
Methods: One male seasonal affective disorder patient (blind to the study design) participated in two 120-hour forced desynchrony experiments and was subjected to six 20-hour days, once during a depressive episode and once after recovery. Core body temperature was continuously measured. During wakefulness, the Adjective Mood Scale was completed at 2-hour intervals.
Results: Sleep-wake as well as pacemaker-related variations of mood were found, both when the subject was depressed and when he was euthymic. Compared with recovery, during the depressive episode the circadian temperature minimum and the circadian mood variation showed phase delays of approximately 1 and 2 hours, respectively.
Conclusions: The data of this first seasonal affective disorder patient, participating in forced desynchrony experiments, may indicate a phase delay of the circadian pacemaker during a seasonal affective disorder episode.