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Later shifts limit sleep, hurt productivity

Filed in
  • Work
  • Shift Work

Sleep Education Archive  |  Jun 15, 2010
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The key to maximizing workplace productivity while minimizing fatigue may be scheduling shift start times that allows workers to sleep right before reporting for duty.

New research suggests shifts that start in the late morning to early afternoon work best for employees. Start times between 8 p.m. and 12 a.m. may limit sleep and harm performance.

Sleep can be difficult to come by during the late night shifts because the timing conflicts with the body’s early evening circadian process.

According to the findings employers would benefit by rescheduling shift starting times to maximize employee alertness and sleep. Lead investigator Angela Bowen suggests a change in public policy may be necessary. Government regulations that limit the number of hours worked would also include provisions for shift start times.

“Shifts of equal duration differ in how fatiguing they are depending on the time of day when they are scheduled,” said Bowen. “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 used a mathematical formula based on a sleep regulation model that predicts the effects of sleep and wake times on sleep quality and waking fatigue. The researchers used the formula to see the effects of 24 start times, each varying by one-hour increments. The hypothetical work schedule lasted six days. Each shift was nine hours and started at the same time each day.

For those with no choice but to start their shifts during the undesirable late evening hours, the key is to find a sleep schedule that works. Past studies have suggested overnight workers go to sleep in the late morning hours immediately after work and wake up before the start of the early evening peak. On days off, it’s desirable to provide a compromise, by going to sleep at about 3 a.m.