Leo Sher, M.D.

Our research work, “A longer biological night in long sleepers than in short sleepers” was published 20 years ago in the January 2003 issue of the Journal of Clinical Endocrinology and Metabolism (1).

Habitual sleep duration varies considerably among people. We wanted to determine whether individual differences in sleep duration are associated with systematic differences in the duration of the biological night that is programmed by the circadian pacemaker and reflected in the nocturnal interval of circadian rhythms in neuroendocrine function, body temperature, and arousal.  Young, healthy long sleepers (sleep duration >9 hours) and short sleepers (sleep duration <6 hours) were studied under constant environmental conditions and in the absence of sleep.

The nocturnal intervals of high plasma melatonin levels, increasing cortisol levels, low body temperature, and increasing sleepiness were longer in long sleepers than in short sleepers. The maxima in cortisol and sleepiness exhibited a close relationship to habitual wake-up time, which occurred approximately 2.5 hours later in long sleepers than in short sleepers. The results of our study indicate that the circadian pacemaker programs a longer biological night in long sleepers than in short sleepers. Individual differences in the circadian pacemaker’s program may contribute to the variability of sleep duration in the general population.

In 2004, the authors of this research study received a major International Award for this work. Daniel Aeschbach, Ph.D., Leo Sher, M.D., Teodor T. Postolache, M.D., Jeffery R. Matthews, M.D., Michael A. Jackson, M.S. and Thomas A. Wehr, M.D. received The Finalist Award of The Endocrine Society and Pfizer, Inc. International Award for Excellence in Published Clinical Research in The Journal of Clinical Endocrinology and Metabolism in 2003.

Reference

1. Aeschbach D, Sher L, Postolache TT, Matthews JR, Jackson MA, Wehr TA. A longer biological night in long sleepers than in short sleepers. J Clin Endocrinol Metab. 2003 Jan;88(1):26-30. doi: 10.1210/jc.2002-020827.