AJP - Regulatory, Integrative and Comparative Physiology, Vol 250, Issue 4 708-R711, Copyright © 1986 by American Physiological Society

ARTICLES

Response of hamster circadian system to transitions between light and darkness

H. E. Albers

The effects of exposure to sudden transitions from dark to light (DL) and light to dark (LD) were determined on the free-running circadian activity rhythm of Syrian hamsters. The activity rhythm was phase delayed by 1-2 h by DL transitions provided during the 12-h interval before activity onset (subjective day). In contrast, DL transitions produced phase advances of approximately 1 h 2-12 h after activity onset. LD transitions tended to produce phase advances throughout the circadian cycle. During the subjective day, LD transitions resulted in phase advances of up to 4 h. After the onset of activity, LD transitions produced phase advances of a lesser magnitude than during the subjective day. In addition, some phase delays were also observed. When the phase shifts produced by DL and LD transitions were combined additively these transitions could account for the phase shifts previously reported for brief pulses of light.

This article has been cited by other articles:

				M. M. Canal and H. D. Piggins Resetting of the hamster circadian system by dark pulses Am J Physiol Regulatory Integrative Comp Physiol, March 1, 2006; 290(3): R785 - R792. [Abstract] [Full Text] [PDF]