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Side Effects from Light Box Therapy

Headaches, Mood Changes May Result from Phototherapy


Updated September 30, 2013

Written or reviewed by a board-certified physician. See About.com's Medical Review Board.

If you have been advised to use a light box to treat your circadian rhythm disorder or seasonal affective disorder (SAD), you may wonder if there are any potential side effects with light box therapy. Fortunately, there are very few side effects with this type of phototherapy and if they do occur, they are reversible once therapy is stopped.

Some of the potential side effects that may occur include:


The light box itself may prove bothersome, inciting a case of photophobia (literally, "fear of light"). If you have this symptom, you may experience a light sensitivity that may even cause eye pain. You may find that the light is irritating and something you simply feel compelled to avoid.


A headache may result from use of a light box, especially if you are prone to migraine headaches.


Curiously, the light box may actually incite a case of fatigue. This may occur if your circadian rhythm becomes shifted inappropriately by using the light in the evening. Your body may suddenly be compelled to sleep during the day and as a result you will naturally feel fatigued.


In some people, the use of a light box may result in increased irritability. You may find yourself losing your patience with others, becoming annoyed, and unexpectedly snapping at them.


There are situations where a light box can actually provoke an episode of hypomania. Mania is a period of elevated mood and increased activity. It often occurs cyclically with bipolar disorder. In predisposed individuals, the light box may cause a milder form of a manic period called hypomania.


Finally, the light box itself may cause difficulties falling or staying asleep called insomnia. Again, this likely relates to a shift in the circadian rhythm and the body's desire to sleep. If the light box is used at the wrong time, such as in the evening, it may result in improper timing of sleep.

Ways to Alleviate Side Effects

Many of these symptoms might be improved by taking a few simple steps. First, you might simply increase the distance you are sitting from the light box. Additionally, it might be necessary to take short breaks or even shorten the session times. By reducing the amount of time that you are being exposed, the side effects might go away.

For those with sensitive skin or a tendency to mania such as in bipolar disorder, it may be best to simply avoid light box phototherapy all together. If you have questions or concerns, you should speak with your doctor about your treatment and possible alternatives.

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