A reader asks:

I have a number of related questions. 1. This is my first year using a light box. How do I know when to stop? 2. Or should I taper off — by how much and over how many days? 3. Now that it is getting lighter earlier (in February), should the time of my light sessions change? 4. I think I may also have mild on-going depression. If I want to do light therapy all year, should I limit use in summer? 5. Is there any correlation in prognosis among your various treatments? i.e., if I only partially respond to light, will I also only partially respond to ions, or might ions be a better choice? Do ions work for year-round depression, or only seasonal?


It is very difficult to respond to such a dense set of questions in q&a format, but we’ll give it a try:

  1. For winter depression, one can try discontinuing treatment at the time of year remission has previously occurred. This differs greatly among individuals. On average, SAD patients like to continue treatment until the end of April in order to avoid risk of relapse. If you slump when you discontinue, you can always start up again for a few more weeks.
  2. Just stop.
  3. There should be no need to adjust timing as the season changes.
  4. If you are using light therapy for year-round depression, you need to experiment with varying the light dose. If you find yourself “too high” come spring and summer, reduce exposure duration to see if you calm down without losing the benefit.
  5. Some people respond selectively to light or negative ions, while some respond to both. (And some to neither!) Current clinical trials at Columbia and Wesleyan indicate that both light and ion treatments are effective for year-round depression, as compared with a placebo control.