Journal of Clinical Endocrinology & Metabolism, Vol 81, 3270-3277, Copyright © 1996 by Endocrine Society

ARTICLES

Progressive elevation of plasma thyrotropin during adaptation to simulated jet lag: effects of treatment with bright light or zolpidem

U Hirschfeld, R Moreno-Reyes, E Akseki, M L'Hermite-Baleriaux, R Leproult, G Copinschi and E Van Cauter
Department of Medicine, University of Chicago, Illinois 60637, USA.

It is well known that TSH secretion is modulated by sleep and circadian rhythmicity, but effects of abrupt shifts of the sleep-wake and dark- light cycles such as occur in jet lag and shift work have not been investigated. The present study examines alterations in the 24-h profiles of plasma TSH and thyroid hormones following an 8-h advance shift achieved without enforcing prolonged sleep deprivation. The effects of bright light exposure or sleep facilitation with zolpidem were investigated in separate studies performed in the same subjects. Each study involved blood sampling at 20-min intervals for 68 h and included a baseline period with dim light during waking hours and 2300- 0700 h bedtimes in total darkness. The 8-h shift was achieved by advancing bedtimes to 1500-2300 h. In the course of adaptation to the shift, TSH levels increased progressively in all three studies because daytime sleep failed to inhibit TSH and nighttime wakefulness was associated with large TSH elevations. The overall elevation of TSH tended to be paralleled by a small increase in T3, but not free T4, levels. In the absence of treatment, mean TSH levels following awakening from the second shifted sleep were more than 2-fold higher than during the same time interval following normal nocturnal sleep (2.10 +/- 0.22 mU/L vs. 1.04 +/- 0.14 mU/L; n = 8, P < 0.001). Bright light exposure limited the overall increase of TSH, and mean TSH levels at the end of the study were lower than in the absence of treatment (P < 0.03). Treatment with zolpidem during the first shifted night limited the overall increase in TSH levels during the following waking period (P < 0.05), but the beneficial effect was no longer significant following the second shifted night. Thus, the jet lag syndrome may be associated with a prolonged elevation of peripheral TSH levels that may be limited by treatment with bright light exposure or hypnotic facilitation of sleep.

This article has been cited by other articles:

				S. W. Kok, F. Roelfsema, S. Overeem, G. J. Lammers, M. Frolich, A. E. Meinders, and H. Pijl Altered setting of the pituitary-thyroid ensemble in hypocretin-deficient narcoleptic men Am J Physiol Endocrinol Metab, May 1, 2005; 288(5): E892 - E899. [Abstract] [Full Text] [PDF]

				U. Holmback, A. Lowden, T. Akerfeldt, M. Lennernas, L. Hambraeus, J. Forslund, T. Akerstedt, M. Stridsberg, and A. Forslund The Human Body May Buffer Small Differences in Meal Size and Timing during a 24-h Wake Period Provided Energy Balance Is Maintained J. Nutr., September 1, 2003; 133(9): 2748 - 2755. [Abstract] [Full Text] [PDF]

				A. Caufriez, R. Moreno-Reyes, R. Leproult, F. Vertongen, E. Van Cauter, and G. Copinschi Immediate effects of an 8-h advance shift of the rest-activity cycle on 24-h profiles of cortisol Am J Physiol Endocrinol Metab, May 1, 2002; 282(5): E1147 - E1153. [Abstract] [Full Text] [PDF]

				R. Leproult, E. F. Colecchia, M. L’Hermite-Balériaux, and E. Van Cauter Transition from Dim to Bright Light in the Morning Induces an Immediate Elevation of Cortisol Levels J. Clin. Endocrinol. Metab., January 1, 2001; 86(1): 151 - 157. [Abstract] [Full Text]

				B. Goichot, L. Weibel, F. Chapotot, C. Gronfier, F. Piquard, and G. Brandenberger Effect of the shift of the sleep-wake cycle on three robust endocrine markers of the circadian clock Am J Physiol Endocrinol Metab, August 1, 1998; 275(2): E243 - E248. [Abstract] [Full Text] [PDF]

				E. Van Cauter, R. Moreno-Reyes, E. Akseki, M. L'Hermite-Baleriaux, U. Hirschfeld, R. Leproult, and G. Copinschi Rapid phase advance of the 24-h melatonin profile in response to afternoon dark exposure Am J Physiol Endocrinol Metab, July 1, 1998; 275(1): E48 - E54. [Abstract] [Full Text] [PDF]