Fatigue Hitting Hard on Your Night Shift? 

Get a blast of bright light! But, be careful, you don’t want to mess up your biology by tricking your brain into thinking it’s daytime. An increasing amount of research is demonstrating that exposure to blue light can have a significant impact on the melatonin and cortisol levels in your brain as well as your internal body clock[1], effectively telling your brain that you are working a day shift during the night. If you do this often enough, and for an entire shift-working career, it can increase your risk of some pretty nasty diseases like diabetes, metabolic syndrome and even cancer. That’s right, cancer. The International Agency for Research on Cancer, the World Health Organization’s specialized cancer agency, classifies shift-work as a probable carcinogen due to the effect of light on melatonin[2].

So why did I say get blast of bright light? Because bright light between 750 and 1000 lux can reverse your night shift fatigue and increase your alertness[3]; and, if the light does not have blue in it, you get the positive effects without the negative effects on melatonin, cortisol and your internal body clock.

A narrow wavelength band of blue light between 470 and 480nm seems to cause the negative effects[1]. It’s usually too expensive to change all the lighting in a workplace to special non-blue equipment. A better solution is to wear eyeglasses that filter out all light below 480nm. If you surf around the Internet, you’ll find a few Web sites selling these glasses.  Before you buy, make sure they provide proof that their filtering works.

light spectrum

The next time you are feeling fatigued, step out of the dark and into bright light with your special blue light filtering glasses on and you’ll lessen the hard hitting blow of fatigue and feel more alert. The effects should even last for a little while after you have to step back into the dark. This means shift-workers who work in dark environments like pilots, train operators, and police officers can use this tip too by taking frequent breaks in brightly illuminated environments with their glasses on.


[1] See for example: Rahman, S., Kollara, A., Brown, T., & Casper, R. (2008). Selectively filtering short wavelengths attenuates the disruptive effects of nocturnal light on endocrine and molecular circadian phase markers in rats. Endocrinology, 149, 6125-6135.

[2] International Agency for Research on Cancer (2010). Monographs on the Evaluation of Carcinogenic Risks to Humans: Painting, firefighting and shiftwork. Lyon France: WHO Press.

[3] Campbell, S. & Dawson, D. (1990). Enhancement of nighttime alertness and performance with bright ambient light. Physiology and Behavior, 48(2), 317-320.