Showing posts with label seasonal affective disorder. Show all posts
Showing posts with label seasonal affective disorder. Show all posts

Friday, August 15, 2008

Definition of light therapy

What is light therapy ?

  • A type of phototherapy in which the subject’s eyes are exposed to light free of IR and UV.
  • The light dosage is expressed in Lux (light unit per surface unit) over a given time

What is a Lux ?

The Lux is the unit of lighting per surface unit. A given surface receives one Lux when it is situated perpendicularly at a distance of 1 meter from a 1 candela light source.

Examples :

  • A moonlit night: 0.5 Lux
  • A well lit apartment : 200 to 400 Lux
  • A cloudy sky outdoors : 25.000 Lux
  • A sunny day outdoors: 50.000 to 100.000 Lux