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Light therapy for depression: What to know

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How it worksLight therapy and SADLight therapy and mental healthHow long?Side effectsMedicationsAlternative therapiesSummary
Light therapy is an experimental treatment for depressive disorders. It works by targeting high functioning areas in your brain that help regulate mood.
Medically reviewed by Nicole Washington, DO, MPH
Written by D. M. Pollock
Updated on

Alternative therapies for depressive disorders are gaining popularity, and light therapy — also called phototherapy — is a noninvasive option involving sitting close to a special light source. This may help improve symptoms of depression.

Seasonal Affective Disorder (SAD) is a common depressive disorder that may benefit from light therapy. It can develop in the transition between fall and winter, when gray skies and shorter days take over, causing feelings of sadness, lethargy, and hopelessness.

Light therapy may also help treat other mental health conditions.

How does light therapy work?

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The use of light to help manage depressive feelings goes back centuries. Over the last 30 years, bright light therapy (BLT) has a growing amount of clinical research and has proven effective in treating some mental health conditions.

Depressive disorders can be due to low serotonin levels. Serotonin is a neurotransmitter that carries messages between the brain and the rest of your body.

While BLT has yet to be fully understood, experts believe it works by mimicking outdoor sunlight. BLT extends the time that your eyes process the light and causes positive changes to your circadian rhythm — your 24-hour physical, mental, and hormonal cycle.

The changes that BLT makes to your circadian rhythm may help improve serotonin levels in your bloodstream by boosting the activity of serotonin receptors and helping reduce depressive symptoms. These physiological effects can also help improve sleep.

According to 2019 research, BLT is most effective in the morning and typically consists of a light box with fluorescent tubes and a reflector. The setup is typically table-mounted, but you can experience the effects through special glasses, which may be more convenient.   

Light therapy and SAD

Light-sensitive receptors in the retina (a part of the eye) transport information on the amount of light around you to the part of your brain responsible for mood regulation, called the suprachiasmatic nucleus.

SAD is a form of temporary depressive disorder, often triggered by shorter daylight hours when the brain receives fewer light signals. This decline in daylight hours can also affect your circadian rhythm, causing sleep difficulties and lower serotonin levels.

The 2019 research noted above found that nearly 70% of individuals with mild SAD symptoms and 40% with severe symptoms responded well to BLT therapy. Due to its efficacy in treating SAD symptoms, doctors now often recommend this as a first-line treatment.

Light therapy and other mental health conditions

In the last 20 years, research has begun into the effects of BLT on other mental health conditions.

There are many different studies demonstrating the effectiveness of BLT in reducing depressive symptoms in people with nonseasonal depression, even showing that BLT is twice as effective in reducing depression symptoms than a placebo.

A 2018 review of six studies describes how as little as 30–60 minutes of BLT exposure for 6 weeks, at intensities varying from 1,200–10,000 Lux, is effective in treating depressive symptoms in older adults. A Lux is equal to a 1-meter (m) square surface illuminated by a single candle from 1 m away.

Other mental health conditions that BLT can help treat include:

  • Bipolar disorder: This condition can cause both manic and depressive episodes. There are limited alternative treatment options for bipolar disorder, and although BLT may help stabilize your mood, there is a low risk of a manic switch. A manic switch is a manic episode that happens within 8 weeks of recovering from an acute depressive episode. While the risk is low, speaking with a psychiatrist before trying new treatments is best for your safety and overall well-being.
  • Eating disorders: People with binge-eating disorder may benefit from BLT treatment, improving disordered eating and mood. However, more research is necessary to understand how much exposure you need for light therapy to be effective. 
  • Antenatal depression: A 2019 review notes a small study in which light therapy effectively reduced depressive symptoms during pregnancy.
  • Attention deficit hyperactivity disorder (ADHD): BLT may help to improve impulsivity, mood, and attention in people with ADHD, reducing symptoms by 15%.

How long should you use light therapy?

If you are receiving BLT for SAD, you will typically need to continue your regimen throughout the winter months until the daylight hours increase. A prescribing healthcare professional will often tailor their advice to your specific needs.

The amount of time you spend using BLT will depend on the intensity of your light source. For example, if your light source is 10,000 Lux, you will typically need 30 minutes of light exposure daily. This will increase to 1–2 hours for a light source of 2,500 Lux.

What are the side effects?

Although side effects from light therapy are rare, you may experience the following:

  • changes to your sight, like blurry vision
  • headaches
  • difficulty sleeping, which you can avoid by only using light therapy after waking
  • tiredness
  • agitation
  • eyestrain

Medications for SAD and mental health conditions

If you experience severe, therapy-resistant symptoms of SAD, a doctor or healthcare professional may prescribe antidepressant medications.

Typically, antidepressant treatment for SAD will begin at the start of winter and can take up to 6 weeks for you to begin experiencing positive effects.

Selective serotonin reuptake inhibitors (SSRIs) are the most common antidepressant types for SAD. They can help boost your brain’s serotonin levels and may include:

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Other therapies for mental health conditions

There are many different options to treat SAD and other mental health conditions. These can include talking therapies, like:

  • Cognitive behavioral therapies (CBT): This aims to transform unhelpful thoughts and feelings so you can better manage your day-to-day activities.
  • Counseling: This involves discussing your worries and concerns with a professional therapist to help identify the causes.
  • Behavioral activation: Sometimes, your behaviors can magnify your symptoms, and behavioral activation teaches you how to counter these behaviors to your benefit.


SAD is a common depressive disorder that develops in the winter months when daylight hours decline. Light therapy is a medication-free alternative to antidepressants that is effective for some people in reducing symptoms of depression.

It can take as little as 30 minutes each winter morning to keep depressive symptoms at bay.

Research shows it may also be effective in treating other mental health conditions, such as antenatal depression and ADHD.

Download the free Optum Perks Discount Card to save up to 80% on some prescription medications.

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