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Ann Emerg Med. 1994 Nov;24(5):928-34.

Relationship of day versus night sleep to physician performance and mood.

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  • 1Department of Surgery, School of Medicine, Stanford University, CA.



To document and analyze the quality and quantity of emergency physicians' sleep as a function of day and night shift work, and to compare cognitive and motor performance and mood during day and night shifts.


Six physicians were monitored for two 24-hour periods. One period consisted of daytime work and nocturnal sleep and the second consisted of daytime sleep and nighttime work.


The emergency department of Stanford University Medical Center and physicians' homes.


Six attending emergency physicians.


Ambulatory polysomnographic recorders continuously gathered EEG, electro-oculogram, and electromyograph data throughout each observation period. Physicians filled out hourly mood ratings and completed a set of two performance tests five times throughout the day.


Physicians had significantly less sleep (496.6 minutes versus 328.5 minutes, P = .02) when sleeping during the day as compared with sleeping at night. Significant performance decrements were also found. Physicians working nights were slower at intubating a mannequin (31.56 seconds versus 42.2 seconds, P = .04) and were more likely to commit errors as their shift progressed (P = .04). Physicians in both conditions were more likely to make errors during a simulated triage test toward the end of their shifts (P = .02). Subjects also rated themselves significantly less sleepy (P < .01), happier (P < .01), and more clear thinking (P < .01) when working day versus night shifts.


Attending emergency physicians get less sleep and are less effective when performing manual and cognitive tests while working night shifts with day sleep compared with working day shifts with night sleep.

[PubMed - indexed for MEDLINE]

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