A Phase Response Curve to Single Bright Light Pulses in Human Subjects

The circadian pacemaker is differentially sensitive to the resetting effects of retinal light exposure, depending upon the circadian phase at which the light exposure occurs. Previously reported human phase response curves (PRCs) to single bright light exposures have employed small sample sizes, and were often based on relatively imprecise estimates of circadian phase and phase resetting. In the present study, 21 healthy, entrained subjects underwent pre- and post-stimulus constant routines (CRs) in dim light (approximately 2-7 lx) with maintained wakefulness in a semi-recumbent posture. The 6.7 h bright light exposure stimulus consisted of alternating 6 min fixed gaze (approximately 10 000 lx) and free gaze…

• NA
  National Aeronautics and Space Administration
• DK
  Deutsches Krebsforschungszentrum
• NH
  National Heart, Lung, and Blood Institute
• NI
  National Institute of Mental Health
• NC
  National Center for Research Resources