Light Strategies for Shift Workers: Night Shifts and Rotating Schedules

Bright light during night shifts, combined with darkness on the way home and a dark bedroom for daytime sleep, is the best-studied light strategy for shift workers. Meta-analyses find small to medium reductions in sleepiness and large shifts of the body clock, and about half an hour more sleep. Most of the evidence comes from small or simulated studies, and the right plan depends on whether you work permanent nights or rotate.

This page summarizes research for general information. It is not medical advice. Light boxes are not suitable for everyone, including some people with eye conditions or bipolar disorder. If you are very sleepy at work or on the drive home, talk to a clinician and your employer; drowsy driving is dangerous.

What the meta-analyses show

The 2022 review summed up evening light as “tentative yet promising.” No review established a single best dose.

Permanent nights: the compromise approach

Full adaptation to nights leaves you out of step on days off. A series of simulated night-shift studies tested a middle path: delay the clock just enough that the sleepiest time moves out of the shift and into the first half of daytime sleep.

• Study 2 (2008): 31 young adults had intermittent bright light during night shifts (75 or 120 minutes in total per shift), dark sunglasses outdoors, scheduled dark sleep, and outdoor light on waking. Their melatonin onset moved to about 00:00–1:00, and they did better on a reaction-time task than controls.
• Study 4 (2009): 19 healthy adults had four 15-minute bright light pulses per night shift, dark sunglasses outdoors, dark bedrooms and an afternoon outdoor light brake to stop the clock delaying too far. Their melatonin onset ended at about 3:22, close to the 3:00 target, and those who reached the target performed better on night shifts.

These were lab simulations in healthy young people who slept at home, not long-term workplace trials.

How much does partial adaptation matter? In a related study of young adults on simulated night shifts (Smith, Fogg & Eastman, 2009), 12 were not re-entrained, 21 were partially re-entrained and 6 were completely re-entrained. By the end of roughly a week of nights with a weekend break, both the partial and complete groups had much better mood, fatigue and performance than the group that was not re-entrained, close to daytime levels. Partial adaptation did about as well as full adaptation.

The target in the final study was a melatonin onset of 3:00, which places the sleepiest time at about 10:00, inside the daytime sleep period, for shifts running 23:00 to 7:00.

Rotating schedules

The Working Time Society consensus gives schedule-specific advice. Its key line: “In slowly rotating night shift schedules bright light appears most suitable when used in connection with the first three night shifts.” It adds that orange glasses on the commute home improve these interventions. For fast-rotating schedules, it favors not shifting the clock at all: less light at night and plenty of natural daylight during the day.

Light timing by shift pattern

The Working Time Society full review and the simulated-shift studies give enough detail to sketch schedules. Treat these as templates to discuss with your employer or a clinician, not tested prescriptions.

The review explains the logic: bright light between 06:00 and 09:00 advances the clock or blocks the delay, so orange glasses that block light below 525 nm in that window help the clock keep delaying. For permanent night workers it recommends holding the delay on days off with a bedtime around 04:00.

Coming back to days is its own problem. The review describes offshore oil workers who estimated it took 5 days to recover after 14 night shifts in a row. With bright light during the day, most readapted within three days, but the authors warn against light too early in the day, before lunch, which can shift the clock the wrong way.

Within a single night shift

NIOSH guidance for nurses suggests more light in the first half of the shift, just by spending time in brightly lit areas, and less in the second half to make sleeping easier, unless you are very sleepy, when bright light can help you stay alert.

It also flags a conflict with the sunglasses advice. Sunglasses can block the alerting effect of light, which could make drowsy driving worse, so NIOSH says the safest approach is to use them after a night shift only if someone else drives you home.

A practical plan consistent with the evidence

• During the night shift: intermittent bright light, from a light box or bright workplace lighting, as used in the studies.
• Commute home: sunglasses or orange-tinted glasses in daylight, as in the studies, only if you are alert or not driving, and never at the cost of seeing the road clearly.
• Daytime sleep: a dark bedroom. The 2022 expert consensus recommends no more than 1 lux melanopic EDI where you sleep, so use blackout curtains or an eye mask.
• Days off: some afternoon outdoor light, the light brake used in the 2009 study, keeps the clock from drifting too late.

Related: jet lag light protocol, evening light and sleep, the light and circadian rhythm guide and the complete sleep guide.