Light Therapy, Sunglasses May Help Shift Workers

A structured sleep schedule, timing exposure to light and strategic use of sunglasses may help night-shift workers adjust to their schedule — and be able to keep a closer-to-normal schedule on days off, a small study suggests.

Working nights disrupts the body's natural circadian rhythms, and studies have shown that this can lead to sleep problems and fatigue at work, as well as longer-term health problems.

Night-shift workers can retrain their bodies to reverse the normal sleep/wake cycle, but in real life, most people want to be awake on their days off.

In the current study, published in the journal Sleep, researchers attempted to partially adjust people's circadian rhythms, so that they would be more alert for nighttime work but still able to have a near-normal schedule on days off.

Mark R. Smith and Dr. Charmane I. Eastman of Rush University Medical Center in Chicago recruited 24 healthy adults to go through a simulated night-shift schedule — staying awake from 11 p.m. to 7 a.m. for three nights, then taking two days off, and finally going through four more "night shifts."

The researchers had one group go through a process designed to partially adjust their circadian rhythm. During the night shift, they were exposed to light boxes for five, 15-minute periods; when they went outside after work, they wore dark glasses to limit their light exposure.

Next, they followed a specific sleep schedule: dozing from 8:30 a.m. to 3:30 p.m. on the first two days of the night shift, then switching to 8:30 a.m. to 1:30 p.m. on the third day. On the next two days — their days off — the volunteers slept from 3 a.m. to noon, giving themselves a wakeful afternoon.

The rest of the volunteers served as a control group and had no sleep- schedule restrictions and normal indoor lighting during the night shift.

In tests of work performance, Smith and Eastman found that their experimental group outscored the control group when it came to reaction time, memory and other on-the-job abilities.

By their last night shift, in fact, they performed as well as they had during daytime tests taken at the beginning of the study.

"The major finding of this study was that complete physiological adaptation to a night shift and day sleep schedule does not appear necessary in order to improve night shift alertness and lengthen daytime sleep," Smith said in a written statement.

The bottom line for employers, he and Eastman say, is that relatively simple and cheap measures may be able to boost worker productivity, while still allowing employees to have a closer-to-normal schedule on their days off.

The researchers will next look at whether the improvements seen in this study can be maintained over a longer period.

"These will be important steps towards convincing employers and shift workers that these interventions are feasible and worthwhile," they conclude.