Light Therapy for Sleep

If you suffer from circadian sleep rhythm disorders, light therapy may be able to help you regain a healthy sleep schedule

By Nicole Gleichmann

Do you ever feel like your ideal sleep schedule doesn’t match up with what society or your employer expects of you? Perhaps you are tired all day, but come midnight, you are wide awake. Or maybe your eyelids get heavy before the sun even sets.

Having an unusual sleep pattern is actually more than just an annoyance. It can be indicative of a circadian rhythm sleep disorder.

The American Academy of Sleep Medicine explains that “circadian rhythm sleep disorders all involve a problem in the timing of when a person sleeps and is awake.” There are many variations of these sleep disorders, but two of the most common are:

The key similarity between all such syndromes is that they involve a disruption in your circadian rhythm, and result in you not being able to fall asleep and wake up naturally at the specific times you would like to.

Fortunately, some people might find relief with something known as light therapy. Read on to learn more about what light therapy is and how you can use it for better sleep.

Light Exposure and Your Circadian Rhythm

You’ve probably heard of your circadian rhythm and know that it has something to do with when you sleep and wake up. Simply put, it’s your biological clock that influences body temperature, sleep, hormone regulation, and more.

All of these things together tell your body when to get sleepy and when to wake up. One hormone controlled by this process is the sleep hormone melatonin. Your circadian rhythm tells your body when to produce melatonin, and the amount of melatonin in your system controls when you feel sleepy.

What you might not know is that your circadian clock is largely controlled by your exposure to light.

Before humans figured out how to make light available anytime we wanted it, we evolved to use light and darkness to inform our sleep-wake cycles. In the absence of alarm clocks, humans still managed to fall asleep and wake up on regular schedules because our bodies told us what to do.

Additionally, in modern society, we expect ourselves to wake and sleep at the same specific times throughout the year, even though the hours of daylight change dramatically from one season to the next. This means that even if your body clock is on point during the summer, the darker fall and winter months might bring some circadian rhythm disturbances.

This influence of light on our sleep-wake cycle evolution is still very significant. If you are having problems with your circadian rhythm, not only might your use of light be the cause (you’ve probably been told not to look at screens before bed), but it also might be the solution.

Light Therapy for Sleep Disorders

Bright light therapy has become a popular treatment for a variety of sleep disorders. During bright light therapy for sleep, exposure to bright light is used to alter brain chemicals that impact sleep and mood, resetting the circadian rhythm.

How it Works

Light therapy is performed by intentionally exposing one’s self to a high intensity light for a predetermined amount of time, at the same time each day. The effects aren’t immediate, but with consistency in your treatment, your circadian rhythm can shift.

While there is no conclusive evidence to prove that light exposure at specific times of the day works better for different conditions, anecdotal evidence and common sense support the use of certain schedules.

Delayed Sleep Phase Syndrome

If you’re a later sleeper and riser, you may have delayed sleep phase syndrome, or DSPS. This disorder is common among young people, though there are no solid figures regarding the percentage of people suffering from this syndrome.

DSPS is treated by using light therapy first thing in the morning on a set schedule. Generally accepted treatment schedules are 10,000 lux for at least 30 minutes a day or 2,500 lux for at least 2 hours.

The goal of this schedule is to decrease melatonin production first thing in the morning so that you can feel more awake, and your body will eventually perform a phase shift, allowing you to both fall asleep and wake up earlier.

Advanced Sleep Phase Syndrome

Common amongst older adults, ASPS is characterized by sleep episodes earlier than desired, and awakening very early in the morning. People suffering from ASPS will often wake as early as 2 or 3 in the morning and find themselves unable to fall back asleep.

The most common time light therapy for ASPS is performed in the late afternoon or evening. This suppresses melatonin production early in the day, giving you the energy to stay awake until a more desirable bedtime.

How to Perform Light Therapy for Sleep

So, now you know what time of day to utilize bright light therapy depending on what syndrome you’re dealing with. But what is the best light source to use? What color light? How much light should you use, and for how long?

Light Dosage

The exact amount of light and time you spend performing light therapy should be discussed with your doctor or sleep specialist. Particularly if you have any eye or skin problems, consult with a doctor to make sure you will not be putting yourself at risk by performing this therapy.

That said, the generally accepted treatment schedules are 10,000 lux for at least 30 minutes a day or 2,500 lux for at least 2 hours.

This can vary based on the color of light or type of light therapy device you use, however, so do not take these numbers and run with them. Create a treatment plan based on your doctor’s advice and the manufacturer recommendations for the device and you choose.

Light Color

Most light therapy devices use full-spectrum light, meaning you can’t discern a color. When you see the measurements in lux, these are assuming full-spectrum light. However, blue light has especially strong effects when it comes to telling your brain to wake up.

That said, for older adults, one study suggests that green light might be more effective due to an increase in the filtration of blue light as we age that’s caused by an increased clouding of the lens of the eye with age. As a result, blue-green light is often used.

Red light has the opposite effect of blue, green, and full-spectrum light, and is often paired with bright light therapy or used on its own in the hours before bedtime in order to encourage sleep.

Light Therapy Devices

You have a few treatment options when it comes to the device you want to use. Whichever method you choose, consult both your doctor and the manufacturer’s guidelines to ensure you are using the device safely and effectively.

The most common sources of bright light for light therapy are:

  • Light box
  • Light visor
  • Natural light

Light boxes are the most common device used. Typically, the process involves working or sitting in front of a light box. You should not look directly at the light box, but rather allow the light in indirectly.

People do everything from working on their computers to watching TV to reading books while performing bright light therapy.

Light visors are another alternative, which allow for greater freedom to move around while using them. Because the light is so close to your eyes, the wattage can be much lower.

The last light source here is one you’re pretty familiar with — the sun! That’s right, bright light therapy doesn’t necessarily need to be performed with an artificial light source.

Depending on the time of year and weather conditions, you may be able to simply spend time outdoors and reap the benefits of natural light. This is another discussion to have with your doctor, as he or she can help you determine whether this will be sufficient and help you create a treatment schedule.

A Brighter Future for Your Sleep

Whether you suffer from an advanced or delayed sleep phase, bright light therapy can help you shift your natural sleep schedule and regain more healthy sleep and a more normal life.


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