Night-Shift Naps Improve ER Performance

Researchers at Stanford University (Palo Alto, CA, USA) conducted a night-shift study of 42 residents and nurses (occupations equally divided) who worked three consecutive night shifts at a Stanford hospital ER. Twenty-one participants were randomized to a control group (no nap) and 21 to a group with a 40-minute nap opportunity at 3 a.m. All participants were free of sleep disorders at the start of the study and completed sleep-wake diaries for a total of 11 days, including two testing days. As a whole, the group reported that their optimum sleep time was a mean of nine hours.

As measured by the psychomotor vigilance test (a test of sustained attention and simple visual reaction time), at 7:30 A.M. the nap group had fewer performance lapses. In fact, a nap increased the speed with which the participants completed a simulated intravenous insertion by 20 seconds. In the mood profile test, the nappers reported more energy, less fatigue, and less sleepiness. However, measures of tension, depression, confusion, and anger, were the same for both groups. Immediately after the nap at 4 A.M., the still-sleepy nappers did less well on a memory test. However, the investigators said that this finding reversed by the end of the night shift and was probably due to temporary grogginess, suggesting the importance of a wake-up period after a nap to address potential sleep inertia.

Nevertheless, the randomized study that compared nappers with non-nappers working the night shift was not all positive. The nappers did not exceed the nonnappers in all parameters, and during post-shift driving simulator tests even the nappers had catastrophic lapses in motor skills. The findings were reported in the November 2006 issue of the Annals of Emergency Medicine.

"The impact of work-hour reduction and schedule changes on attention failures, medical errors, and intern sleep have gained wide attention,” concluded lead author Rebecca Smith-Coggins, M.D., of Stanford, and colleagues. "Being up for 24 hours has the same effect as being legally drunk.”




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