Working at night results in a misalignment between the sleep-wake cycle and the output of the hypothalamic pacemaker that regulates the circadian rhythms of certain physiologic and behavioral variables. We evaluated whether such physiologic maladaptation to nighttime work could be prevented effectively by a treatment regimen of exposure to bright light during the night and darkness during the day. We assessed the functioning of the circadian pacemaker in five control and five treatment studies in order to assess the extent of adaptation in eight normal young men to a week of night work. In the control studies, on the sixth consecutive night of sedentary work in ordinary light (approximately 150 lux), the mean (+/- SEM) nadir of the endogenous temperature cycle continued to occur during the night (at 3:31 +/- 0:56 hours), indicating a lack of circadian adaptation to the nighttime work schedule. In contrast, the subjects in the treatment studies were exposed to bright light (7000 to 12,000 lux) at night and to nearly complete darkness during the day, and the temperature nadir shifted after four days of treatment to a significantly later, midafternoon hour (14:53 +/- 0:32; P less than 0.0001), indicating a successful circadian adaptation to daytime sleep and nighttime work. There were concomitant shifts in the 24-hour patterns of plasma cortisol concentration, urinary excretion rate, subjective assessment of alertness, and cognitive performance in the treatment studies. These shifts resulted in a significant improvement in both alertness and cognitive performance in the treatment group during the night-shift hours. We conclude that maladaptation of the human circadian system to night work, with its associated decline in alertness, performance, and quality of daytime sleep, can be treated effectively with scheduled exposure to bright light at night and darkness during the day.
Source Information
Department of Medicine, Harvard Medical School, Brigham and Women's Hospital, Boston, MA 02115.
This article has been cited by other articles:
Santhi, N., Aeschbach, D., Horowitz, T. S., Czeisler, C. A.
(2008). The Impact of Sleep Timing and Bright Light Exposure on Attentional Impairment during Night Work. J Biol Rhythms
23: 341-352
[Abstract]
Higuchi, S., Motohashi, Y., Ishibashi, K., Maeda, T.
(2007). Influence of eye colors of Caucasians and Asians on suppression of melatonin secretion by light. Am. J. Physiol. Regul. Integr. Comp. Physiol.
292: R2352-R2356
[Abstract][Full Text]
Klerman, E. B., Hilaire, M. St.
(2007). Review: On Mathematical Modeling of Circadian Rhythms, Performance, and Alertness. J Biol Rhythms
22: 91-102
[Abstract]
Revell, V. L., Burgess, H. J., Gazda, C. J., Smith, M. R., Fogg, L. F., Eastman, C. I.
(2006). Advancing Human Circadian Rhythms with Afternoon Melatonin and Morning Intermittent Bright Light. J. Clin. Endocrinol. Metab.
91: 54-59
[Abstract][Full Text]
Zeitzer, J. M., Khalsa, S. B. S., Boivin, D. B., Duffy, J. F., Shanahan, T. L., Kronauer, R. E., Czeisler, C. A.
(2005). Temporal dynamics of late-night photic stimulation of the human circadian timing system. Am. J. Physiol. Regul. Integr. Comp. Physiol.
289: R839-R844
[Abstract][Full Text]
Landrigan, C. P., Rothschild, J. M., Cronin, J. W., Kaushal, R., Burdick, E., Katz, J. T., Lilly, C. M., Stone, P. H., Lockley, S. W., Bates, D. W., Czeisler, C. A., the Harvard Work Hours, Health and Safety Group,
(2004). Effect of Reducing Interns' Work Hours on Serious Medical Errors in Intensive Care Units. NEJM
351: 1838-1848
[Abstract][Full Text]
Gronfier, C., Wright, K. P. Jr., Kronauer, R. E., Jewett, M. E., Czeisler, C. A.
(2004). Efficacy of a single sequence of intermittent bright light pulses for delaying circadian phase in humans. Am. J. Physiol. Endocrinol. Metab.
287: E174-E181
[Abstract][Full Text]
Rivkees, S. A.
(2003). Time to Wake-Up to the Individual Variation in Sleep Needs. J. Clin. Endocrinol. Metab.
88: 24-25
[Full Text]
Wright, K. P. Jr., Hull, J. T., Czeisler, C. A.
(2002). Relationship between alertness, performance, and body temperature in humans. Am. J. Physiol. Regul. Integr. Comp. Physiol.
283: R1370-R1377
[Abstract][Full Text]
Horowitz, T. S., Cade, B. E., Wolfe, J. M., Czeisler, C. A.
(2001). Efficacy of bright light and sleep/darkness scheduling in alleviating circadian maladaptation to night. Am. J. Physiol. Endocrinol. Metab.
281: E384-E391
[Abstract][Full Text]
Sumaya, I. C., Rienzi, B. M., Deegan, J. F. II, Moss, D. E.
(2001). Bright Light Treatment Decreases Depression in Institutionalized Older Adults: A Placebo-Controlled Crossover Study. J. Gerontol. A Biol. Sci. Med. Sci.
56: M356-M360
[Abstract][Full Text]
Klerman, E. B., Goldenberg, D. L., Brown, E. N., Maliszewski, A. M., Adler, G. K.
(2001). Circadian Rhythms of Women with Fibromyalgia. J. Clin. Endocrinol. Metab.
86: 1034-1039
[Abstract][Full Text]
Leproult, R., Colecchia, E. F., L’Hermite-Balériaux, M., Van Cauter, E.
(2001). Transition from Dim to Bright Light in the Morning Induces an Immediate Elevation of Cortisol Levels. J. Clin. Endocrinol. Metab.
86: 151-157
[Abstract][Full Text]
Kayumov, L., Brown, G., Jindal, R., Buttoo, K., Shapiro, C. M.
(2001). A Randomized, Double-Blind, Placebo-Controlled Crossover Study of the Effect of Exogenous Melatonin on Delayed Sleep Phase Syndrome. Psychosom. Med.
63: 40-48
[Abstract][Full Text]
Rimmer, D. W., Boivin, D. B., Shanahan, T. L., Kronauer, R. E., Duffy, J. F., Czeisler, C. A.
(2000). Dynamic resetting of the human circadian pacemaker by intermittent bright light. Am. J. Physiol. Regul. Integr. Comp. Physiol.
279: R1574-R1579
[Abstract][Full Text]
Arendt, J.
(2000). Melatonin, Circadian Rhythms, and Sleep. NEJM
343: 1114-1116
[Full Text]
Brown, E. N., Choe, Y., Luithardt, H., Czeisler, C. A.
(2000). A statistical model of the human core-temperature circadian rhythm. Am. J. Physiol. Endocrinol. Metab.
279: E669-E683
[Abstract][Full Text]
Zeitzer, J. M., Ayas, N. T., Shea, S. A., Brown, R., Czeisler, C. A.
(2000). Absence of Detectable Melatonin and Preservation of Cortisol and Thyrotropin Rhythms in Tetraplegia. J. Clin. Endocrinol. Metab.
85: 2189-2196
[Abstract][Full Text]
ROBERTS, J. E.
(2000). Light and Immunomodulation. Ann. N. Y. Acad. Sci.
917: 435-445
[Abstract][Full Text]
Baehr, E. K., Fogg, L. F., Eastman, C. I.
(1999). Intermittent bright light and exercise to entrain human circadian rhythms to night work. Am. J. Physiol. Regul. Integr. Comp. Physiol.
277: R1598-R1604
[Abstract][Full Text]
Goichot, B., Weibel, L., Chapotot, F., Gronfier, C., Piquard, F., Brandenberger, G.
(1998). Effect of the shift of the sleep-wake cycle on three robust endocrine markers of the circadian clock. Am. J. Physiol. Endocrinol. Metab.
275: E243-E248
[Abstract][Full Text]
Tzischinsky, O., Lavie, P.
(1997). The Effects of Evening Bright Light on Next-Day Sleep Propensity. J Biol Rhythms
12: 259-265
[Abstract]
Mitchell, P. J., Hoese, E. K., Liwen Liu, , Fogg, L. F., Eastman, C. I.
(1997). Conflicting Bright Light Exposure during Night Shifts Impedes Circadian Adaptation. J Biol Rhythms
12: 5-15
[Abstract]
Efinger, J., Nelson, L. C., Walsh Starr, J. M.
(1995). Understanding Circadian Rhythms: A Holistic Approach to Nurses and Shift Work. J Holist Nurs
13: 306-322
[Abstract]
Dijk, D.-J., Boulos, Z., Eastman, C. I., Lewy, A. J., Campbell, S. S., Terman, M.
(1995). Light Treatment for Sleep Disorders: Consensus Report: II. Basic Properties of Circadian Physiology and Sleep Regulation. J Biol Rhythms
10: 113-125
[Abstract]
Campbell, S. S., Dijk, D.-J., Boulos, Z., Eastman, C. I., Lewy, A. J., Terman, M.
(1995). Light Treatment for Sleep Disorders: Consensus Report: III. Alerting and Activating Effects. J Biol Rhythms
10: 129-132
[Abstract]
Eastman, C. I., Boulos, Z., Terman, M., Campbell, S. S., Dijk, D.-J., Lewy, A. J.
(1995). Light Treatment for Sleep Disorders: Consensus Report: VI. Shift Work. J Biol Rhythms
10: 157-164
[Abstract]
Boulos, Z., Campbell, S. S., Lewy, A. J., Terman, M., Dijk, D.-J., Eastman, C. I.
(1995). Light Treatment for Sleep Disorders: Consensus Report: VII. Jet Lag. J Biol Rhythms
10: 167-176
[Abstract]
Minors, D.S., Waterhouse, J.M.
(1994). Deriving a "Phase Response Curve" from Adjustment to Simulated Time Zone Transitions. J Biol Rhythms
9: 275-282
[Abstract]
