A reader asks:

 I’ve noticed that light therapy boxes (LTB’s) have uses for SAD, but I have heard that they can be effective with insomnia. How do you use LTB’s on someone with early, middle or late insomnia — especially late insomnia to stop my brother from waking at 4 a.m. every morning. He doesn’t want to use medications.

Answer:

You are correct that light therapy can alleviate certain forms of insomnia, when the root cause is misalignment of internal circadian rhythms with the day-night cycle. Waking up at 4 a.m. could be due to several other factors, however, in which case light therapy would be ineffective. Diagnosis and treatment supervision by a sleep specialist is advised. A recent medical handbook chapter on the topic, which you might recommend to your doctor, is: Terman M, Terman JS. (2000) “Light therapy,” in Principles and Practice of Sleep Medicine, third edition by Kryger M., Roth T., Dement W., Editors, Philadelphia, W.B. Saunders, pp. 1258-1274.