Overview

• Bright light therapy is an effective treatment for seasonal affective disorder (SAD). The most common light therapy uses a special type of light, called a light box. This is much brighter than a lamp or other light fixture in your home.
• Light therapy is easy and safe. It has few side effects and can be done at home.
• People who have eye problems or who take medicines that cause sensitivity to light should not use light therapy without first consulting a doctor.

How is light therapy done?

Place the light box on a desk or table, and sit in front of it at the specified distance. You can do this while you read, eat breakfast, or work at a computer. The light should reach your eyes, but don't stare at the light box.

Light therapy is usually prescribed for 30 minutes to 2 hours a day, depending on the intensity of the light used and on whether you are starting out or have been using it for a while.

Most light therapy is prescribed at 10,000 lux to be used in the early morning. Studies vary as to whether light therapy at other times of the day is less effective. But some people with SAD (perhaps those who wake up normally in the early morning) should do their light therapy for 1 to 2 hours in the evening, ending 1 hour before bedtime. Your doctor can help you decide which light exposure schedule will work best for you.

Light therapy is usually started in the fall and continued through spring.

When you begin light therapy, your first response will show you whether you need to adjust the intensity or duration. Many people respond to light therapy within 3 to 5 days. If you don't respond to treatment within the first week, you may notice improvement in the second week.

The most common side effects of light therapy include headache, eye strain, and nausea. You may be tired during the first week because of changes in your sleep-wake patterns, but this will usually go away after about a week.