Light Therapy for Shift Workers: How to Adjust Your Body Clock

It's 7am and your night shift has just ended. The sun is up, traffic is building, and everyone around you is starting their day just as yours comes to an end. You're tired, but the daylight reaching your eyes sends your body a signal that promotes wakefulness.

Whether you work in a hospital, a factory, security or behind a screen, night or irregular schedules can put your sleep-wake rhythm under strain. If you've ever worked nights, started very early in the morning or followed a rotating schedule, you may know the feeling of being pulled in two directions: your body is ready for rest while your environment is sending signals that promote wakefulness.

Light therapy can help you incorporate controlled light exposure into an irregular schedule and better align your sleep-wake rhythm. But how you use it depends on your working hours, your sleep schedule and the time of day. Here's how to approach it in different situations.

Your body runs on an internal clock of roughly 24 hours, mainly synchronized by environmental signals, with light playing a major role. This is the circadian rhythm at work: exposure to light and darkness helps signal to your body when it is time to be awake and when it is time to sleep.

Shift work can create a mismatch between your working hours and your biological clock. You may be awake at a time when your body would normally promote sleep, then try to sleep when environmental signals are promoting wakefulness. This mismatch can make sleep more difficult and contribute to feelings of fatigue or sleepiness during periods of activity.

Night-shift workers can face this challenge particularly after their shift. Getting home when daylight is already strong can promote wakefulness when the goal is to sleep. The mismatch between working hours, light exposure and your biological clock can therefore make it harder to sleep and adapt to an irregular schedule.

Light therapy has been studied as an approach for using light more strategically, depending on when you want to promote wakefulness or sleep.

The principle of light therapy is to expose your eyes to bright light at a specific time. Depending on when the exposure takes place, light can influence the signals that synchronize your circadian clock and contribute to changes in your sleep-wake rhythm.

Light therapy protocols can use different intensities, durations and light characteristics. Traditional light therapy lamps are often used at 10,000 lux, but intensity alone does not determine the effect of an exposure.

Depending on when it is used, light can contribute to advancing or delaying the circadian rhythm. Timing is therefore particularly important for shift workers: exposure to light that promotes wakefulness during a shift may not have the same effect if it takes place just before a sleep period.

The goal is to match the timing of the exposure to your own working and sleeping hours, rather than to the schedule of a typical day.

Here's how this can translate into different schedules. If you work nights, light can be used at certain points during your shift to influence wakefulness and circadian signals. If you start work very early in the morning, exposure after waking can help reinforce the signal that the day has begun. With rotating schedules, the timing of light exposure can be adjusted gradually as your working hours change.

The Sleep Foundation also recommends considering the timing of light exposure when managing irregular work schedules.

This is where things become more practical. When you work shifts, the timing of your light exposure is particularly important. The goal is to match it to your own working and sleeping hours. Here are some practical guidelines for the most common situations.

If you work nights: Use light therapy during the first part of your shift, for example around 10pm or 11pm if your shift starts in the evening. The aim is to promote wakefulness during the period when you are working, while avoiding unnecessary exposure to bright light as your shift comes to an end.

After your shift, reduce your exposure to bright light as much as possible. Sunglasses can help limit your exposure to outdoor light on the way home, provided you do not use them while driving if you are feeling sleepy. NIOSH also recommends managing light exposure during and after night shifts, including getting more light during work and reducing exposure after the shift.

Once you are home, a dark bedroom and dim lighting can also help create an environment that is more conducive to sleep. Avoid a light therapy session in the hours immediately before your planned sleep period.

If you work early mornings: If you get up around 4am or 5am to start your day very early, a light therapy session can be incorporated into your routine after waking. With Luminette, the session duration depends on the intensity selected: the different settings correspond to sessions of 20, 30 or 45 minutes.

You do not need to remain still during the session. You can use Luminette while doing some of your usual morning activities, such as having breakfast or getting ready.

If you work rotating shifts: Gradually adjust the timing of your sessions as your working hours change, rather than changing everything at once. When possible, keep a relatively stable routine for a few days before adjusting the timing again. The aim is to give your sleep-wake rhythm time to adapt progressively to the new schedule.

This is where a wearable device can be useful. The Luminette 3 and Luminette 2 use blue-enriched white light, with a peak around 468 nm. Their position close to the eyes allows you to keep your hands free during a session and continue with certain everyday activities.

The Drive is also designed for use while travelling. For people whose schedules do not follow a typical daily routine, these formats can make it easier to incorporate a light therapy session into everyday life.

You can compare the different light therapy devices to find the format that best fits your schedule.

Light plays an important role, but other habits can also make daytime sleep easier.

Create a dark sleeping environment. Blackout curtains, a sleep mask or a combination of both can help limit light exposure during your rest period.

Keep your sleep and wake times as regular as possible. Very different schedules on days off can make it harder to adapt to an already irregular rhythm.

Watch your caffeine intake. Avoid consuming caffeine in the hours before your planned sleep period if you find that it interferes with falling asleep.

Tell the people around you about your sleep window. Family, housemates and friends cannot protect a schedule they do not know about. A note on the door and silenced notifications can help avoid unnecessary interruptions.

Finally, consistency is important when incorporating light into a shift-work routine. Rather than using it only when fatigue is particularly strong, try to maintain an exposure schedule that is consistent with your working hours. This can help make light therapy a consistent part of your daily routine.

Shift work asks your sleep-wake rhythm to adapt to working hours that do not always match the natural signals of the day. Light therapy can help incorporate controlled light exposure into this routine and may contribute to better alignment of the circadian rhythm when the timing of exposure is appropriate.

A portable format such as Luminette can make this easier to integrate, particularly when working hours change regularly or when your day is difficult to organize around a stationary lamp.

The key is to choose an appropriate time for your light exposure and incorporate it into a routine that fits your working and sleeping hours.