If you work nights, your body clock is still set for daytime. It wants you awake when the sun is up and asleep in the dark, which is the opposite of your schedule. Light is the strongest signal your body clock responds to, so controlling when you see light and dark is the most practical way to help it shift. This guide explains a light plan for night workers, based on studies of sunglasses, bright light and blackout bedrooms.
In this article
The short answer
- Bright light during the first part of your night shift helps push your body clock later.
- Morning sunlight on the way home pulls it back. Dark sunglasses block much of that effect.
- A fully dark bedroom helps you sleep longer during the day.
- In studies, workers who shifted their body clock even partly felt and performed much better at night.
- Keep a similar sleep time on days off to avoid undoing the shift.
Why night work is so hard on the body
Your body clock (circadian rhythm) runs on a roughly 24-hour cycle. It makes you sleepiest in the early hours of the morning, around 3 to 6 AM, and more alert during the day. On a night shift, you are trying to work during your body’s lowest point and sleep during its most alert time.
The result for many workers is short, broken day sleep and heavy sleepiness at work. Over years, night work is linked with higher risks of weight gain, type 2 diabetes and heart disease. Some workers develop shift work disorder, where insomnia and sleepiness persist despite trying to sleep enough. For tips on getting through the hardest hours, see our guide to the 3 AM to 5 AM slump.
How light moves your body clock
Light reaching your eyes is the main signal that sets your body clock. Timing matters:
- Light in the evening and first half of the night pushes your clock later. This is what a night worker wants.
- Light in the early morning pulls your clock earlier, back towards a daytime pattern. This is the light most night workers get on the commute home.
The body clock is most sensitive to blue light, the kind found in daylight and in cool white LEDs. That is why sunglasses, and especially blue-blocking lenses, can help in the morning.
What the studies found
Nurses on night shifts (2002): 10 nurses worked under bright light for part of their shifts and wore tinted goggles on the way home. Their body clocks shifted by about 9 to 11 hours over about 12 shifts, roughly twice as much as nurses who worked normally.
Simulated night shifts (2003): 67 young adults worked five simulated night shifts. Bright light during the shift, dark sunglasses outside in the day, and an early, regular daytime sleep in a dark bedroom gave the best shift in body clock. Darker sunglasses helped more than normal ones when there was no bright light at work. A melatonin pill before day sleep did not add much.
Mood and performance (2009): people whose body clocks had shifted even partly had much better mood, less fatigue and better performance on night shifts than those whose clocks had not shifted. Their scores were close to daytime levels.
Blue blockers (2009): in a small pilot study, night workers who wore blue-blocking glasses on the way home slept better during the day.
A simple light plan
Try this
- Bright light early in the shift. Work under the brightest light you can for the first half of your shift. A light therapy lamp at your workstation can help if your workplace is dim.
- Dim down near the end. In the last couple of hours of your shift, avoid extra bright light.
- Dark sunglasses on the way home. Put them on before you step outside, even on cloudy days. Wraparound styles block light from the sides. Do not wear very dark lenses while driving if they make it hard to see.
- Go to bed soon after you get home. In the studies, sleep started about 1 to 2 hours after the shift ended.
- Make the bedroom completely dark. Blackout curtains or blinds, tape over gaps, and cover small lights. An eye mask helps too.
- Keep light low when you wake. If you wake to use the bathroom, use a dim night light.
Setting up a dark, quiet bedroom
- Blackout curtains: choose ones that go past the window frame on all sides, or fit blackout blinds inside the frame and curtains on top.
- Noise: daytime is noisy. Earplugs or a steady sound machine can help. Our guide to white noise vs brown noise explains the options.
- Cool room: aim for a cool room, around 60 to 67°F (15 to 19°C), using a fan if needed.
- Phone: silence it and turn the screen away. Let family know your sleep hours.
Days off
Switching back to a normal day schedule on your days off can undo the shift in your body clock. A common compromise in research is to go to bed late (for example 3 AM) and sleep until late morning on days off. This keeps your clock partly on night time while still letting you see daylight and family.
Myth vs fact
Myth: Your body fully adjusts to night work after a few weeks. Fact: Most permanent night workers never fully adjust, mainly because of morning light and switching back on days off. Controlling light can help a lot, even if the shift is only partial.
Other things that help
- A nap before the shift of 20 to 90 minutes can improve alertness at work.
- Caffeine early in the shift, not in the last few hours, so it does not spoil your day sleep.
- Light meals at night. Big meals in the early hours sit heavily and may affect blood sugar.
- Melatonin: some workers use a low dose before day sleep. It may help some people sleep, but in the 2003 study it did not add much to light control. Ask a doctor first.
Safety first
Drowsy driving after a night shift is a real risk. If you feel very sleepy, take a short nap before driving, use public transport, or get a lift. Signs to stop include yawning a lot, drifting in the lane, or not remembering the last few miles.
When to see a doctor
See a doctor if you cannot sleep well during the day despite a dark, quiet room, or if you feel dangerously sleepy at work or while driving. These can be signs of shift work disorder or sleep apnea, which can be treated.
Frequently Asked Questions
Do sunglasses really help night shift workers sleep?
Yes, as part of a plan. In studies, dark sunglasses or blue-blocking glasses on the way home helped body clocks shift, and in one small study workers slept better during the day.
What kind of sunglasses should I use?
Dark lenses that let through little light, ideally wraparound. Amber or orange blue-blocking lenses are another option. Make sure you can still see well enough to drive safely.
Are blackout curtains worth it?
For day sleepers, yes. Even small amounts of light can make day sleep lighter and shorter. Cheap options like blackout liners or foil on the window can work too.
What should I do on my days off?
Try a late schedule rather than a full switch back to days. Going to bed in the early hours and sleeping until late morning keeps your body clock closer to your work schedule.
Does this work for rotating shifts?
It is harder. With fast-changing shifts, it is usually better to focus on good sleep after each shift and on naps, rather than trying to shift the body clock fully.
Conclusion
You cannot change the fact that night work goes against your biology, but you can make it easier. Bright light early in the shift, dark sunglasses on the way home, and a truly dark bedroom are cheap, simple steps with real research behind them. Even a partial shift in your body clock can make nights feel much less like a struggle.
Sources
- Boivin DB, James FO. Circadian adaptation to night-shift work by judicious light and darkness exposure. J Biol Rhythms, 2002.
- Crowley SJ, et al. Combinations of bright light, scheduled dark, sunglasses, and melatonin to facilitate circadian entrainment to night shift work. J Biol Rhythms, 2003.
- Smith MR, et al. A compromise circadian phase position for permanent night work improves mood, fatigue, and performance. Sleep, 2009.
- Sasseville A, et al. Wearing blue-blockers in the morning could improve sleep of workers on a permanent night schedule: a pilot study. Chronobiol Int, 2009.
- Boivin DB, Boudreau P. Impacts of shift work on sleep and circadian rhythms. Pathol Biol, 2014.
- National Institute for Occupational Safety and Health. Training for nurses on shift work and long work hours.
