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Reprogramming Your Internal Clock for Shift Work

There’s no denying that the night shift can leave us feeling totally drained. Are there any long-lasting solutions to adapt to the night shift and reduce fatigue? Read on to find out.

In Part 1, we learned about the circadian rhythm and its effect on the brain, body, and sleep. We also learned why shift work goes against most peoples’ natural cycles and how shift work can create disordered sleep and negatively impact our lives.

In Part 2, we’ll examine ways to alleviate some or all of that nighttime fatigue. Here, you’ll find science-backed schedules to reprogram your circadian rhythm so that it better lines up with your work schedule. 


The problem with night-shift work

The fundamental problem with night-shift work is that the circadian rhythm (which, for most people, is set to awake during the day and asleep at night) is not programmed for us to work nights and sleep days. When the mismatch between circadian rhythm and work schedule happens over a long period, it becomes chronic and can lead to sleep deprivation, even if shift workers sleep “enough” during the day. It can also have other effects on our health.

Shift-work sleep deprivation occurs because the best sleep happens when the body temperature is at its lowest, which is usually a few hours before waking (see Part 1). With a circadian rhythm that is not matched up to working nights, shift workers will continue to have their body temperature drop around 5 a.m., just as their shift is wrapping up. They will begin to feel the most tired at this time and their bodies will be sending strong signals to sleep. To make matters worse, many shift workers are then exposed to the rising sun on the drive home. This suppresses sleepiness signals and makes it harder to sleep. All of this culminates in poorer quality and quantity of sleep after shift.


Retraining your internal clock

Retraining the internal clock is something that all shift workers should consider. Retraining works best for people working permanent night shifts, or a combination of evening and night shifts. Not only will retraining help alleviate some of the profound nighttime sleepiness, but it will also help improve the quality of daytime sleep. By reprogramming your internal clock, you are pushing your sleepiest time of day from the later part of your shift to the early morning when you arrive home.

Note: if you are rotating between shifts (day, evening, and night shifts) every few days, then it is not possible to quickly retrain your circadian rhythm for each of these short stints. Instead, it is best to use the techniques discussed here to reduce your fatigue. If possible, try to limit shifts to either days and evenings, or evenings and nights. Of course, this is not always possible.

There are 3 key components to retraining your circadian rhythm: (1) timed exposure to light, (2) timed exposure to dark, and (3) scheduling and consistency.


Timed exposure to light

Exposure to light at key times of night can help shift your circadian rhythm so that you feel more awake at night and sleep better during the day. Researchers are still trying to determine the best wavelength and source of light, but for the moment, many feel that intermittent, bright light is sufficient. Basically, being exposed to bright light prevents melatonin from being released for a while. This pushes the cycle of the circadian rhythm to a later time, helping ward off sleepiness at night and ensure better quality sleep during the day.

  • Try to get lots of natural light before your shift.
  • Purchase a light-therapy box or light-therapy glasses (or set your workstation near a bright overhead light fixture), and try to get one hour total of bright light exposure during the night. It’s not necessary to stare directly at the light, and the light can be blue-wavelength enriched or plain white.


Timed exposure to dark

In addition to exposure to bright light at night, shift workers should try to keep themselves in relative darkness once their shift is over. Many researchers recommend dark glasses for the drive home; however, if this makes you feel too sleepy, then it is important to have someone else drive you.

  • Blue-light-blocking sunglasses should especially be used on the first five days of working nights (but consider always wearing them). They should be worn in the morning on the way home from work. Consider a wrap-around style to block light from the sides.
  • Once home, ensure your room is dark—for more information, check out this piece.


Scheduling and consistency

Find a schedule that works for you and stick to it! People who go back to “normal” sleeping and waking times on days off may be less well-adapted to their night schedule. Shift workers report less drowsiness and better performance at work when they maintain a constant schedule even on their days off. This is important as many shift workers have erratic sleep schedules, sleeping around family and social commitments, or nodding off when they feel sleepy.

  • Aim to sleep about an hour and a half after the end of shift. The sooner you can get to bed, the better. This is because the circadian rhythm does not have to delay as much and there is less potential to be exposed to light.
  • Consider initially getting seven instead of eight hours of sleep to build mild sleep deficit to help with falling asleep faster on subsequent days.
  • Use an afternoon “light brake.” This works by exposing yourself to bright light in the afternoon (sunlight or light-therapy box) when you wake up. A light brake helps train your body to sleep during the day and prevents your circadian rhythm from shifting too much.
  • Keep track of the amount of light you are exposed to and the times of day it occurs to see if helpful patterns emerge.
  • Sleep late on days off (and prevent early morning light exposure) to maintain your retrained circadian schedule. For example, go to bed around 3 a.m. and wake around noon on days off.


Combine bright light during shift, darkness on the way home and at home, and a regular and consistent schedule for best results.


Sample retraining schedules

The following schedule uses the principles of circadian retraining (light, darkness, and scheduling).

Eight-hour shifts, five days in a row

Night shifts 1–4: 

  • Work 11 p.m.—7 a.m. (get 15 min bright light every hour from midnight–4 a.m.)
  • Wear dark glasses on way home
  • Sleep 8:30 a.m.–3:30 p.m.


Night shift 5: 

  • Work 11 p.m.—7 a.m. (get 15 min bright light every hour from midnight–4 a.m.)
  • Wear dark glasses on way home
  • Sleep 8:30 a.m.–2:30 p.m.
  • Bright light brake at 3 p.m.


Days off 1 –2: 

  • Sleep 3 a.m.–noon
  • Bright light brake at 1 p.m.


Twelve-hour shifts, three days in a row

Night shifts 1–2: 

  • Work 7 p.m.—7 a.m. (get 15 min bright light every hour from midnight–4 a.m.)
  • Wear dark glasses on way home
  • Sleep 8:30 a.m.–3:30 p.m.


Night shift 3: 

  • Work 7 p.m.—7 a.m. (get 15 min bright light every hour from midnight–4 a.m.)
  • Wear dark glasses on way home
  • Sleep 8:30 a.m.–2:30 p.m.
  • Bright light brake at 3 p.m.


Days off 1 –4: 

  • Sleep 3 a.m.–noon
  • Bright light brake at 1 p.m.


Note that experts recommend extreme caution in driving when retraining the circadian cycle. It is not recommended to drive during the first week of circadian retraining, as you may be extremely sleepy during this time.


How your workplace or employer can help

Experts in shift-work sleep disorder recommend that shifts are either slowly rotating forward or never rotating. Ideally, shifts should never be rapidly rotating or intermittent. In other words, night workers should always work nights. Alternatively, if employees do shift, they should slowly rotate forward, clockwise: e.g., work two weeks of days, then two weeks of evenings, then two weeks of nights. 

Workplaces should consult with lighting engineers to determine the optimal lighting for their space and the tasks required, especially if they employ shift workers. Light engineers are critical to workplace safety and wellness.

Employers should offer staff an option for a safe ride home after a shift (e.g., pay for a taxi) to minimize light exposure and reduce road accidents.

Employers should ensure staff have access to rooms for eating, napping, and recharging if needed. Facilities should offer healthy and well-balanced food options at a reduced cost for shift workers. They should also offer exercise equipment along with educational information with examples of schedules to help workers retrain for night work.


In conclusion, make your nights bright and your days dark. Get an hour of bright light during the night. Wear light-blocking glasses after work and make your room dark for sleep. Get bright light when you wake up. If possible, delay sleep for one hour (but wind down) after getting home to maximize sleep. Try to be consistent. These tips will help you feel more energized, alert, and productive. They will also help improve workplace safety and efficiency at night.

Last updated: 2024-03-16

Picture of Emma Farley, MD CCFP

Emma Farley, MD CCFP

On her journey to become a physician, Dr. Emma Farley worked many nights shifts caring for patients while balancing a heavy study workload. As a medical writer and editor at Night Shift Wellness, she creates practical and evidence-based articles for readers.

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