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Phototherapy and Delayed Sleep Phase Syndrome (DSPS)

Phototherapy, also known as light therapy, bright light therapy, or blue light therapy, is a popular buzzword these days for people trying to improve their sleep health.

What is it, exactly? And who can it help?

What is phototherapy?

Phototherapy is a proactive regimen of controlled, intentional light exposure using specific kinds of light across the spectrum to help reset the circadian system.

The eyes are exposed to intense (but safe) levels of light (either natural or artificial) following a specific protocol.

Light therapy is used to advance or delay sleep for people who do not fall asleep or wake up at appropriate times during the night or day.

Their sleep-wake cycles occur at times which are incompatible with their lifestyles.Treating these circadian shifts means resetting those rhythms so they can return to normal life.

Phototherapy is a common treatment that requires effort on the part of the patient to participate in this reset. It may or may not also incorporate other kinds of therapies as prescribed by a knowledgeable sleep specialist.

Light spectrum 101

To understand how it works, you need to know a few things about the light spectrum.

  • Blue light.This is the color of light in the spectrum which most powerfully interacts with the brain to align our circadian rhythms. It is a popular form of consolidated spectrum light used in phototherapy.

  • White light.This is more commonly known as full-spectrum or all-spectrum light. White light occurs when all the colors in the spectrum merge into one. It’s been used in phototherapy for a long time.

  • Green light.This is another visible wavelength of light which can interfere with the circadian system in much the same way as blue light.

  • Red light.This is considered “warm light” and safe to view at night. Incandescent bulbs are red spectrum lighting and are perfect to use in night lights.

  • Amber light.This warm light is considered safe to encounter at night as it doesn’t alter melatonin production. Amber light filters are often placed on blue spectrum light sources as “blue blockers” for this reason. Backlit device screens now feature amber filters, as do video gaming or computer glasses.

How does phototherapy work?

Light therapy uses the body’s natural alignment with the planet’s 24-hour light-dark cycle as a focus for resetting the circadian clock.

Each of us has an internal body clock that tells us when to go to sleep and when to wake up.

This clock is known as the suprachiasmatic nucleus(SCN). It relies on light exposure through the eyes for synchronization.

When you encounter daylight, that information travels from photoreceptors in your eyes to the brain, signaling for you to stay awake.

As the natural light dims, the eyes send this new information to the SCN, which signals to the pineal gland in the brain to begin the process of releasing melatonin into the bloodstream.

Melatonin is our “sleep hormone,” and the pineal gland will produce it in extended release in the evening until we fall asleep. By late morning, our rhythms shift and less melatonin is released while cortisol, an alertness hormone, begins to stir the body into wakefulness.

People with misaligned circadian rhythms do not fall asleep at the normal times. Either they are delayed in phase shifting between wakefulness and sleep, so that they fall asleep 2 or more hours after the rest of us, or their phase shift has advanced, making them tired too early in the evening. In either case, both wake up at inappropriate times and are tired all the time due to misaligned rhythms.

A crash course in basic home-based light therapy

For people with significant problems with DSPS, the very best option is to work with a sleep specialist to build a customized therapeutic approach for advancing your sleep phase.

While consumers might feel it’s “good enough” to simply buy a light box, the reality is that if they don’t use it correctly, it will not work. Key details, like brightness, timing, frequency, and duration, and strategies for using the light on a specific schedule, are critical to the success of phototherapy.

Each sleep center operated by Sound Sleep Health has specialists who can help you best diagnose and treat your phase shift problems.

The following process describes a very basic home-based light therapy strategy that can be built upon and customized to each individual’s needs with the help of a sleep specialist.

  1. Clean up your sleep hygiene.This won’t fix your DSPS, but it will help enhance your efforts to do so. Improve your sleep conditions and change your bad habits.
  2. Plan A: Natural light.Get into the practice of exposing yourself to bright light first thing in the morning. Grab a cup of coffee and sit outside, if possible, or go for a short walk. A common recommendation is 20 minutes, but your doctor will know what’s best for you.
  3. Plan B: Artificial light.If the weather isn’t cooperating (we live in Seattle, after all: light comes at a premium!), consider investing in some form of bright light lamp.

    Note: Normal household lighting is not bright enough to do the work. It is important to use a light that has the ultraviolet components filtered out, or eye damage can result.

  4. Expose yourself.The Circadian Sleep Disorders Network recommends exposures of 10,000 lux for between 30 minutes and 2 hours. What you will need will depend entirely upon your sleep specialist’s recommendation. Don’t guess, get some help.
  5. Timing is critical. For people with DSPS, using the light in the morning is key. Your physician may ask you to rise a little earlier each time, in specific increments over a period of a few weeks, in order to maximize the therapy’s benefits.
  6. Lux matters.Using lower intensity light (less than 10,000 lux) will require much longer exposure. You must also sit at the distance recommended by the light manufacturer or else the effects wont be meaningful. And knowing the difference between white and blue light also matters as to the length of exposure.
  7. No staring at the sun, please.You don’t need to stare at your light source, simply face it while going about your business.
  8. Stick to the schedule.Your sleep specialist will help you determine the schedule you need to repeat this process of light exposure in order to achieve an improved sleep schedule.
  9. Bright light avoidance in the evening is the other side of the coin in phototherapy. Avoiding sources of blue spectrum light, in particular, is not only complementary to the efforts made in the morning to reset your rhythms, but it’s critical for evening melatonin production.
  10. Complementary therapies.For some people, DSPS may be part of a conditioned response at bedtime that may require cognitive behavior therapy for insomnia (CBTi) to correct. The prescription and dosing of melatonin supplements in the evening, or stimulants during the day, may also be part of a successful treatment protocol for DSPS. Each individual is different, which makes it critical that phototherapy take place under the supervision of a sleep specialist.

Phototherapy for sleep disorders

Delayed sleep phase disorder is not the only sleep problem that can be treated with bright light therapy. Insomnia and advanced sleep phase disorder (ASPS) also benefit from phototherapy. Those with “free running” or non24 sleep-wake disorder (in which the sleep phases are always different, day after day) may find bright light therapy at least temporarily useful. Also, people with jet lag disorder could benefit from well-timed light therapy.

Other benefits of phototherapy

  • Vitamin D.Exposure to bright light results in the body making more of this critical substance.

  • Elevated mood. People use phototherapy to treat the problem of Seasonal Affective Disorder (SAD) because it has been shown to improve emotional health and provide relief for people in darker climates or during the winter who have problems with depression.

Phototherapy: What to avoid

  • Are you mood disordered?Don’t apply phototherapy before talking to your physician first. Phototherapy can triggermanic episodes.
  • Have eye problems or headaches?This is something to mention to your sleep specialist to ensure phototherapy is right for you.
  • All phototherapy lamps are not equal.There are lamps used for skin health and lamps for newborn babies. Make sure you are using the right lamp for your needs. Avoid UV lamps (which dispense harmful UVb rays) to prevent eye damage.

Phototherapy is more than just sitting in front of a bright light. Your best bet for dealing with a delayed sleep phase problem is to consult your sleep physician about the right approach. They can take the mystery out of light exposure scheduling, intensities, and other factors you might not have considered.


American Academy of Sleep Medicine
Circadian Sleep Disorders Network
Environmental Health Perspectives
Harvard Medical School Division of Sleep Medicine
Psychology Today
Sleep Review
Stanford Health Care

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