Can exposure to bright light help prevent shift worker fatigue?

Montreal — Exposing night shift workers to bright light before work begins may improve their sleep, lessen fatigue and lead to fewer errors on the job.

That’s according to researchers from McGill University, who recruited 57 full-time nurses from three Montreal hospitals and divided them into two groups. One group underwent an experimental intervention of evening light exposure and morning light avoidance to improve circadian rhythm alignment. The other group modified its diets to improve alertness and reduce sleep disturbances.

Each morning and evening over a 30-day period, the researchers measured the nurses’ fatigue, work-related errors, sleepiness, mood, and sleep duration and quality. The participants worked a rotating schedule of day and night shifts during the same week.

The nurses who took part in 40 minutes of bright light exposure from a portable light box before their night shifts saw a 67% reduction in on-the-job errors. In contrast, the control group showed only a 5% reduction.

Additionally, the bright light exposure group saw a small improvement in mood compared with the control group. Both groups experienced reductions in fatigue and sleepiness, as well as a small increase in sleep duration.

“Interventions like the one we studied are relevant to a large population of workers, since between a quarter and a third of the world’s employees do some form of shift work,” lead study author Mariève Cyr, a medical student at McGill, said in a press release. “Although we focused on nurses working rotating schedules, our results may apply to other types of shift workers as well.”

The study was published online in the journal Sleep Health.