Chronobiology International — Informa Healthcare’s journal on how biological rhythms affect the systems of living things — has published a new study which shows that the use of blue light blocking eyeglasses can help facilitate daytime sleep for shiftworkers.

The study recruited permanent nightshift workers from Canada Post’s distribution center in Quebec City. The study used two groups — a summer group and a fall/winter group — in order to reduce the chances of the results being affected by seasonal daylight differences. Both groups were asked to wear specialized blue light blocking glasses when outdoors. The glasses were designed by the team to block the transmission of blue light because this is the portion of the light spectrum that most effects the body’s circadian clock and sleep-wake rhythm. They also wore light monitors on their wrists.

Both groups obtained 30 minutes more sleep within the same time in bed, suggesting fewer awakenings and better sleep efficacy.

“The results of the study imply that improving light exposure at night combined with wearing blue blockers in the morning could represent a simple and elegant means of improving the daytime sleep of permanent night workers,” says Alexandre Sasseville, lead author of the article in Chronobiology International.

“It is well established that our circadian clock — or ‘body’ clock — is most sensitive to the blue portion of the visual spectrum,” continues Alexandre. “This light suppresses melatonin production, the substance our body clock uses to know that it is nightime and time to fall asleep.”

A good day’s sleep for those who work through the night is not just about getting enough beauty sleep or feeling less grumpy upon waking. It’s about the health of the worker and the safety of those around him or her.

“Night work is not only associated with acute and chronic health problems, but also social impairment, lower performance, increased risk of error, industrial accidents and road accidents,” explains Alexandre. “The most frequent complaints among shiftworkers are the lack of proper sleep during the day and lower vigilance while working at night. The two are highly correlated.”