When we use lightboxes to treat SAD, we are “reprogramming” our body’s Circadian Rhythm. This is the body’s 24hour clock that tells it when to sleep and when to wake up. We need to program our Circadian Rhythm so that it better matches our day.
Treating some sleep disorders is very much the same process. In fact, in many cases the symptoms are the same. Have trouble falling asleep at night and also getting up in the am? Then you are probably sleep phase delayed and should use the bright light in the morning. If you fall asleep too early and wake up too early, then you are probably a sleep phase advanced and should use the light in the afternoon. Of course these are generalizations and in order to get this right, you should seek the help of a qualified professional.
Here is a great site that is packed full of a ton of great info and links on Sleep Disorders. http://sleepeducation.com/Treatment.aspx?id=4. Not only is there information on sleep disorders, but a quick finder for a sleep clinic in your area. Check it out.