The optimal time for Light Therapy varies from person to person. It is dependent on the individual’s internal clock. This can be established using Morningness-Eveningness Questionnaire (MEQ).
Based on results from the Morning Eveningness Questionnaire for your normal pattern of sleeping and waking, Light Therapy is usually prescribed between 06:45 and 09:00. The duration of Bright Light Therapy usually lasts for 30 minutes.
A dose of 10,000 lux of light is required.
You should sit about 1 foot (about 30 cm) from the light box (unless the manufacturer dictates otherwise). At this distance, you should be able to comfortably eat a meal, read a book or use a laptop. You should not stare into the light. Equally you should not keep your head down too far. You should maintain this distance from the light throughout the prescribed duration.
Keep a weekly record of your symptoms to determine if you are improving. For example, complete the “PHQ-9” questionnaire which is widely available by searching.