Light therapy proves to be most effective when using the proper combination of these three elements: Intensity, Duration and Timing.
Intensity of light boxes are recorded in lux (a measure of the amount of light you receive at a specific distance from a light source). Light boxes for light therapy produce between 2,500 lux to 10,000 lux. Most commonly they produce 10,000 lux.
Light therapy on average involves daily sessions ranging from 30 minutes to 2 hours. When first using light therapy it is wise to start at small increments of time such as 15 minutes, and then to gradually work up to longer periods. For most people, light therapy is most effective if used in the morning, soon after waking up, rather than in the evening. Using light therapy at night may disrupt sleep.