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Light therapy for depression

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Updated on January 25, 2021

Light therapy is a treatment for certain types of depression and other conditions. It requires the user to spend time near a light therapy box that gives off bright artificial light like natural outdoor light. This isn’t your typical house lamp.

It’s also known as phototherapy or bright light therapy (BLT).

Depression and light therapy

Light therapy is best known as a treatment for seasonal affective disorder (SAD), also known as major depressive disorder (MDD) with seasonal pattern.

It’s also used for treating types of depression that aren’t tied to the seasons, and other mental health conditions such as bipolar disorder.


SAD is a type of major depressive disorder. It’s typically triggered by seasonal changes, commonly during fall and winter when there are fewer hours of sunlight in the day.

Some people find the use of a light therapy box provides relief. Others find light therapy more effective when combined with additional treatments, such as psychotherapy or antidepressant medications.

Bipolar disorder

People with bipolar disorder may experience depressive episodes. According to 2018 research, light therapy can be a safe and effective add-on treatment for bipolar disorder depression.

The Mayo Clinic warns that, for some people with bipolar disorder, light therapy may trigger manic and mixed states. If you have bipolar disorder, be sure to talk with your doctor before trying light therapy.

How does light therapy work?

Lack of exposure to sunlight is thought to be linked to mood changes and seasonal depression. Light therapy is meant to compensate for that lack with a light therapy box. Light therapy boxes emit a bright light that mimics sunlight.

According to research, light therapy may help by either correcting your circadian rhythm or increasing serotonin.

A study in 2015 also suggested that light therapy may affect brain chemicals, such as serotonin, linked to sleep and mood.

For SAD, treatments usually take place from early fall to early spring. A typical session lasts 15 to 30 minutes, but length varies based on:

  1. How long you’ve been having the treatments
  2. The strength of the light therapy box
  3. How well you handle the treatment

It’s recommended to use the light therapy box within an hour of waking up in the morning.

Other conditions light therapy is used for

Bright light therapy can be used for conditions other than depression, including:

  • Sleep disorders, such as insomnia
  • Jet lag
  • Dementia
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Risks associated with light therapy

Light therapy is considered generally safe. Side effects, if they occur, should typically be short-lasting and mild.

Side effects may include:

  • Headache
  • Eyestrain
  • Nausea

For people with bipolar disorder, side effects may include:

  • Mania
  • Agitation
  • Hyperactivity
  • Euphoria

Talk with your doctor about light therapy if you have specific conditions or are taking medications that make you light sensitive. For example:

  • You have systemic lupus erythematosus.
  • You have a condition that makes your eyes susceptible to eye damage.
  • You’re taking medications that increase your light sensitivity, such as certain anti-inflammatories or antibiotics.

If you experience side effects, discuss them with your doctor.

Light therapy box features

Although you can buy a light therapy box without a prescription, your doctor may have a specific make and model they suggest. Features to consider include:

  • Brightness/intensity: 10,000 lux is commonly recommended (bright sunlight ranges from 20,000 to 100,000 lux).
  • UV light: To avoid possible eye damage, consider a light box that filters out all or most ultraviolet light.
  • Type: Look for a light therapy box designed specifically for SAD.

Light therapy boxes aren’t regulated by the Food and Drug Administration (FDA), and the cost isn’t typically covered by insurance plans. Before buying, make sure to consider what brightness you need, if the lamp is designed for therapeutic use, and if you have space for it in your home.


Light therapy can be part of an effective treatment for seasonal affective disorder (major depressive disorder with seasonal pattern) and bipolar disorder.

While you don’t need a prescription to buy a light therapy box, you should discuss the idea with your doctor to see if light therapy is an appropriate treatment for you.