Light Box Therapy

If you suffer from a circadian rhythm disorder, including a night owl tendency or depression caused by a seasonal affective disorder (SAD), you may wonder: What is light box therapy? This treatment, also called phototherapy, may be just what you need to sleep better and feel more alert during the day. Phototherapy may be delivered via a light box, but also via special light therapy glasses. How does using this therapy help to improve sleep and mood?

Woman sitting by a light therapy box
JGI / Jamie Grill / Getty Images

What Is a Light Box?

First, it is important to understand what a light box is: a specially designed fixture that produces a soft, steady light. Some light boxes stand independently, but newer technology has integrated the therapy into eyeglasses.

Light boxes are meant to generate a standard wavelength and amount of light. The light may be full-spectrum (appearing white in color but including blue light) or it may generate only blue light, which is known to affect circadian rhythm. This affects sleep and wakefulness periods.

The light of a light box ideally should have an intensity of approximately 10,000 lux to be effective. Light therapy glasses may have a lower light intensity, since the light is delivered directly into the eyes rather than being diffused into a room.

Sleep Disorders Treated with Light Box Therapy

Many problems can occur when the human biological clock becomes misaligned to the natural day-night cycle. This cycle is what promotes sleep at night and alertness during the day. If it's disrupted, a person may develop insomnia or hypersomnia (excessive daytime sleepiness). Various physiological disorders may disrupt circadian rhythm and may be effectively treated with light box therapy, including:

  • Advanced sleep phase syndrome
  • Delayed sleep phase syndrome
  • Jet lag
  • Shift-work sleep disorder
  • Irregular sleep-wake rhythm

The timing of light box treatment may vary with each condition. For example, night owls may benefit most from light exposure in the morning; those who have advanced sleep phase syndrome may need the phototherapy at night. If you have any of these disorders, you may wish to consult with a board-certified sleep physician for proper treatment guidance. Some light therapy devices come with an associated app that can provide support and helpful instructions on how to optimize treatment.

The Role of Light in Mood Disorders

Beyond impacts on sleep, seasonal changes in day length may also cause difficulties with mood. Winter's shorter days and longer nights provide less natural light. Having to start one's day before sunrise, when natural light begins, or face darkness after work, when the sun has already set, may lead to symptoms of depression.

Exposure to bright light in the morning may help to reset your biological clock, but without it, you may feel prolonged sleepiness that lasts late into the morning. Phototherapy may alleviate mood disorders that are worsened by seasonal changes in light exposure.

Symptoms Responsive to Light Box Therapy

Certain symptoms tend to be more responsive to light box therapy. They include:

  • Insomnia
  • Excessive morning sleepiness, or hypersomnia
  • Winter or seasonal depression
  • Lethargy

Responses to treatment vary. Benefits may begin in the first few weeks of therapy, but consistency is key. Patients should use the therapy daily and at the time prescribed. Inconsistent use may have an impact on how effective the treatment will be.

Using Sunlight as Treatment Instead

When possible, it's best to get natural sunlight exposure. The sun provides up to 100,000 lux of full-spectrum light, and this has a far stronger impact on circadian timing. Don't wear sunglasses or a hat or visor: Let the sun shine on your face, but as always, don't stare directly at it to avoid damaging your eyes.

A Word From Verywell

If you believe that you have symptoms or a condition that might be responsive to light box phototherapy, you may wish to consult your physician before selecting a light box. The guidance your physician provides will help you determine the most effective timing and duration of treatment. If you continue to struggle, you may find it helpful to consult with a sleep physician or psychiatrist.

4 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Miller MC. Seasonal affective disorder: bring on the light. Harvard Health Blog.

  2. Auger RR, Burgess HJ, Emens JS, Deriy LV, Thomas SM, Sharkey KM. Clinical practice guideline for the treatment of intrinsic circadian rhythm sleep-wake disorders: advanced sleep-wake phase disorder (ASWPD), delayed sleep-wake phase disorder (DSWPD), non-24-hour sleep-wake rhythm disorder (N24SWD), and irregular sleep-wake rhythm disorder (ISWRD). An update for 2015: an American Academy of Sleep Medicine clinical practice guideline. J Clin Sleep Med. 2015;11(10):1199-236. doi:10.5664/jcsm.5100

  3. Pail G, Huf W, Pjrek E, et al. Bright-light therapy in the treatment of mood disorders. Neuropsychobiology. 2011;64(3):152–162. doi:10.1159/000328950

  4. Sapega S. Get enLIGHTened: why working near a window is good for your health. Penn Medicine.

Additional Reading

By Brandon Peters, MD
Brandon Peters, MD, is a board-certified neurologist and sleep medicine specialist.