Reference Work Entry

Encyclopedia of Aging and Public Health

pp 501-502

Light Therapy

  • Aditi Mehta

Light therapy is most often used in clinical settings, as a treatment for seasonal affective disorder (SAD). SAD is a type of depression that sets in the winter, as the daylight time decreases. The concept of light therapy is based on the existence of a circadian rhythm that refers to 24‐h cycles of rest and activity that involve changes in the body, depending on the time of day or night. During winters, light therapy compensates for the deficit of natural light that is believed to be related to depression.

Light therapy is also sometimes used to treat insomnia; elderly people, in particular, may be good candidates for light therapy. A Japanese study showed significant improvement in behavior problems in patients with dementia who were exposed to morning bright light. This finding was later replicated in other studies.

Light therapy involves exposure to bright light in the range of 1,500–10,000 lux from a source such as a light box. The current recommendation for treatment of SAD is a mi ...

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