ONE PACEMAKER IN SEASONAL AFFECTIVE-DISORDER

Patients with winter seasonal affective disorder (SAD) often have abno rmalities in the resetting of their circadian clock. The circadian cyc le appears to be variable across days among these patients, deviating from the exact 24 hours, and peaking at unstable times. The findings s uggest that the mean free-running circadian period is longer in winter SAD patients compared to healthy subjects. It is hypothesized that th ere would be a singular circadian pacemaker in the patients against th e two pacemakers in healthy subjects.