An Overview of Light Therapy Lamps: Treatment for Seasonal Affective Disorder (SAD)

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Light therapy, which is often administered through light therapy lamps, has been found to be an effective treatment for seasonal affective disorder (SAD), formally diagnosed as major depressive disorder with seasonal pattern in the current Diagnostic and Statistical Manual of Mental Disorders (DSM-5).

This article discusses how light therapy works and why light therapy lamps are so beneficial to people with SAD symptoms—like depression, hopelessness, and fatigue.

A woman sitting in front of a light box to treat seasonal affective disorder (SAD).

IAN HOOTON / Getty Images

What Is Light Therapy?

Bright light stimulates the cells in the retina that connect to the hypothalamus (part of the brain that helps control the body’s daily rhythms).

Lack of adequate bright light, such as during the diminished daylight from fall to spring, can cause problems for people with certain conditions such as seasonal affective disorder (SAD).

One way to mitigate the effects of this reduction in sunlight is to engage in a treatment called light therapy.

Other Names for Light Therapy

Light therapy is also referred to as bright light therapy (BLT) or phototherapy.

Light therapy uses a device called a light box, which emits bright white light that mimics sunlight, to activate the hypothalamus.

Doing this at a certain time every day can help to restore a normal circadian rhythm (the body’s 24-hour sleep-wake cycle) and improve the symptoms associated with SAD.

These boxes typically provide 10,000 lux (a measure of light intensity). For comparison, indoor light is about 100 lux, and a bright sunny day outside is about 50,000 lux, sometimes more.

While primarily used to treat SAD, light therapy may also be helpful for:

  • Chronic depression
  • Antepartum depression (depression in pregnancy)
  • Premenstrual depression
  • Bipolar depression
  • Disturbances of the sleep-wake cycle

Light therapy should be used with caution or may be contraindicated for people with certain health conditions, including:

  • Macular degeneration and some other eye conditions
  • Connective tissue damage
  • Existing skin cancers
  • Diabetes
  • Lupus

Do You Need a Prescription for Light Therapy Lamps?

Light therapy lamps don’t require a prescription, but you should always consult a healthcare provider before using one.

How Are Light Therapy Lamps Used to Treat Seasonal Affective Disorder?

SAD is a type of recurring major depression with a seasonal pattern. Some symptoms of SAD may include:

  • Depression
  • Irritability
  • Social withdrawal/difficulty getting along with others
  • Difficulty concentrating
  • Fatigue/sleeping more than usual
  • Weight gain
  • Increased hunger/carbohydrate cravings
  • A heavy feeling in the arms and legs

Daily light therapy sessions are used to help alleviate these symptoms. The specifics of these sessions include:

  • Sit approximately 12 to 24 inches from the box.
  • Do not look directly at the light.
  • Angle the box to about 30 degrees from the line of gaze.
  • Sessions are usually done first thing in the morning.
  • Treatments are typically used daily from fall to spring.
  • Standard treatment is 10,000 lux for 30 minutes.
  • Alternative treatment is 2,500 lux for one to two hours.

Improvement in symptoms is usually seen fairly quickly, often within days, but treatments must be continued to sustain these effects.

Are There Any Negative Effects From Light Therapy?

There tend to be less severe negative effects seen with light therapy than with antidepressants. Some potential negative effects include:

  • Eyestrain
  • Increased risk of age-related macular degeneration
  • Headaches
  • Irritability
  • Difficulty sleeping

Less commonly, hypomania and suicidal ideation may occur, especially during the first few days of treatment.

How to Choose a Light Therapy Lamp

When choosing your light therapy lamp, keep these things in mind:

  • Adjustable settings: Adjustable dimming and brightness settings allow for variety and versatility.
  • Shape: Choose a lamp that fits in with your environment and suits your needs, be that portability, sturdiness, adjustable height, or other factors.
  • Light intensity: The typical light therapy lamp is 10,000 lux brightness, but other options are available such as multiple brightness settings or modes that allow for gradual adjustments to daytime or nighttime. There are also different types of bulbs to choose from.
  • Timer: A built-in timer eliminates the need for manual timing of each session.

Frequently Asked Questions

How far away should you place a light therapy lamp from you?

The specified distance may vary depending on the device, but the typical distance is 12 to 24 inches.

Always read the manual that comes with your device to ensure you are following the instructions specific to that equipment.

How long does it take for you to respond to light therapy lamp treatment?

You should start to see an improvement in symptoms within the first week of therapy.

One study found an immediate improvement in mood after the first session of light with exposures as short as 20 minutes. While encouraging, this study had limitations, such as a small sample size of 15 participants.

Stopping therapy sessions can make the symptoms reappear.

How often should you use a light therapy lamp?

When using a light that is the recommended 10,000 lux, treatments are usually every day for about 30 to 45 minutes each. They are usually first thing in the morning, from fall to spring.

With lights that aren’t as strong, treatment sessions may be longer. For instance, a daily session may be one to two hours for a 2,500 lux lamp.

A Word From Verywell

Light therapy is a recommended first-line treatment for SAD, with a documented history of helping improve symptoms.

If you suspect you may have SAD, or think you may benefit from light therapy, speak with a healthcare provider to discuss your options and see if light therapy is right for you.

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