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Light Treatment for Seasonal Affective Disorder

Private: Janis L. Anderson, PhD
Contributor Janis L. Anderson, PhD

Do you find in the depths of winter you don’t feel like yourself? Your energy level might be lower. You might feel irritable. Maybe you have difficulty sleeping. If you find yourself experiencing the symptoms of depression but only during wintertime, you could have seasonal affective disorder (SAD).

SAD is a mood disorder in which a person’s depression occurs repeatedly in a particular season of the year – most often people with SAD get depressed in winter when days are short. SAD is a form of depressive disorder and has the usual symptoms. What is unique to the specific SAD diagnosis is the seasonal timing. Evidence-based treatments for SAD include light therapy. This requires the use of a specific type of light box to mimic some features of natural sunlight. Janis L. Anderson, PhD, Department of Psychiatry, Brigham and Women’s Hospital, offers some tips for choosing the right type of light box to treat SAD.

What is the best light box to buy?

Many products have been developed since the 1980s, and several have been used in clinical research studies where they were demonstrated to be effective. However, no one type of bulb or device has been demonstrated superior to all others. The main considerations are cost and safety. In the absence of FDA regulation, it is up to the consumer to look into claims made by vendors. Some wavelengths of light can be hazardous to eyes or skin, so major research centers have avoided ultraviolet-containing “full-spectrum” bulbs and have used blue light only after careful examination of safety data for the specific device. In general, cool-white fluorescent or some LED bulbs have been used successfully by many clinical research centers.

Can I just put special bulbs into my light fixtures at home?

It is difficult to safely construct an effective light treatment device on your own. The high level of light required for daytime use is achieved by using specific reflectors, ballasts, and other components that the average household would not have on hand. Simply putting brighter bulbs into existing light fixtures is likely to be a waste of money. In addition, electrical safety and wavelengths of the lights are important technical concerns affecting safety that many users are not equipped to evaluate.

One form of light treatment that has been studied to some extent is called “dawn simulation.” This treatment uses less intense light in the bedroom as a person is waking up. However, the light needs to gradually increase in intensity so special equipment is used to produce the gradual increase over a period of an hour or so. Also, it must be acceptable to bed partners.

How much light exposure is enough?

The “dose” of a light for affecting SAD is determined by the intensity and wavelengths of light coming from the device, the distance of the user from the device, the time of day relative to the user’s normal schedule, and the length of time the exposure goes on. It is possible to get too much light, which can produce discomfort including feeling “wired,” such as after consuming too much caffeine. Working with an experienced clinician, and starting with general guidelines, many SAD patients arrive at a “dose” that works well for them. Some patients benefit from regularly increasing their exposure to outdoor sunlight after awakening, but the cold weather makes that a challenge.

Here at the Brigham, we are exploring ways to use input from smartphones to inform decisions on when to begin light treatment, and to aid users in selecting the most helpful dose. For many individuals with SAD, the shorter days of fall and winter bring early changes in functioning, such as difficulty getting up in the morning, which can be effectively addressed by starting properly-timed supplemental light exposures.

In summary, light therapy is one proven treatment for controlling symptoms of seasonal affective disorder during fall/winter months. Specialized lights are recommended for therapy to be effective, and prices can approach $200 or more. Some specific features to consider:

  • UV light – Look for lights that block or filter UV light.
  • Illumination “dose”– The recommended dose depends on your distance from the light device and the time of day you are using it. It is important to not wake up extra early in order to get a strong dose of light, as that can upset your daily body rhythm.
  • Light type – White light has been more widely studied.
  • Physician recommendation – Consult with your physician or health care professional. They can help determine whether you are suffering from seasonal affective disorder and evaluate your eyes to make sure that light exposure will be safe for you.

Private: Janis L. Anderson, PhD
Janis L. Anderson, PhD

Janis L. Anderson, PhD, is a psychologist at Brigham and Women’s Hospital and an assistant professor of psychology at Harvard Medical School.

Before you go,

Mental health is a key part of your overall wellness. Get tips on managing mental health conditions and find out how to cope with anxiety, stress and trauma in your daily life. Read more mental health articles.