SAN ANTONIO, June 12 (UPI) — Employees who start work between 8 p.m. and midnight had consistently poorer performance at work — probably due to a lack of sleep, U.S. researchers found.
Lead author Angela Bowen, research assistant at the Sleep and Performance Research Center at Washington State University Spokane, said the study found workers’ sleep lasted from 4.5 hours to 8 hours, depending on when the shift began.
The study predicted the minimum on-the-job fatigue occurred when the shift started at 9 a.m., while maximum fatigue occurred when the work shift began at 11 p.m.
“Shifts of equal duration differ in how fatiguing they are depending on the time of day when they are scheduled,” Bowen said in a statement. “The same limitation on the number of duty hours may be either overly restrictive if during the day or too liberal if during the night.”
The study found those who had a shift begin at midnight did better because they could sleep right up to going to work, while those who started work earlier did worse because the timing conflicted with the body’s early evening circadian process.
The findings were presented at Sleep, the 24th annual meeting of the Associated Professional Sleep Societies in San Antonio.
Copyright 2010 United Press International, Inc. (UPI). Any reproduction, republication, redistribution and/or modification of any UPI content is expressly prohibited without UPI’s prior written consent.