A "Clock for All Seasons" in the Human Brain

A "Clock for All Seasons" in the Human Brain, by Thomas Wehr

Psychobiologist Wehr presents the findings from his research into seasonal changes in the human circadian rhythm.  In particular, he discusses the emergence of bimodal sleep (sleep in two segments) in test subjects who remained in bed, in the dark, for the length of a mid-winter night.

"A 'Clock for All Seasons' in the Human Brain.  Ed. R.M. Buijs, et. al.  Hypothalamic Integration of Circadian Rhythms.  Elsevier, 1996.  319-340.