AJP - Regulatory, Integrative and Comparative Physiology, Vol 245, Issue 4 497-R504, Copyright © 1983 by American Physiological Society
Impact of a circadian clock on the timing of human sleep
A. T. Winfree
This paper redescribes some recordings of human sleep and waking made in
several laboratories during the past decade under conditions of temporal
isolation. Since 1972 it has been noticed that sleep duration depends
mainly on the timing of prior sleep onset relative to a rhythm of 24- to
25-h duration. The present paper emphasizes four additional points: 1) that
the dependence sometimes includes a remarkable discontinuity, 2) that such
dependence is characteristic of a rhythmically modulated threshold process;
3) that the rhythm's period gradually changes in some experiments; and 4)
that no comparable regularity has been detected in the timing of sleep
onset. This last impugns the reliability of models that treat sleep onset
and wake onset as complementary but comparable processes.
