December 2020 | Reviewed by: Shelley Hershner, MD and Reeba Mathew, MD
What is bright light therapy?
Bright light therapy is a treatment for people who have circadian rhythm sleep disorders. Your body has an internal clock that tells it when it is time to be asleep and when it is time to be awake.
This clock is in the brain just above an area where the nerves travel to the eyes. This area is called the suprachiasmatic nucleus or SCN. Your clock controls the circadian rhythms in your body. These rhythms include body temperature, alertness and the daily cycle of many hormones.
The word “circadian” means to occur in a cycle of about 24 hours. Circadian rhythms make you feel sleepy or alert at regular times every day. Some people have a circadian rhythm sleep disorder. This causes their natural sleep time to overlap with regular activities such as work or school.
One thing that “sets” your internal clock is exposure to bright light such as sunlight. Light therapy is used to expose your eyes to intense but safe amounts of light for a specific and regular length of time. In many places, sunlight is not available at the proper time to be used as treatment. Artificial light may be used to affect the body clock in the same way that sunlight does except we often get exposed to artificial light when we normally have darkness.
Light therapy can help someone “reset” a clock that is off. Regular sleep patterns help to keep the clock set at the new time. Light therapy is one part of a treatment plan that should be guided by a sleep doctor.