A reader asks:

 I am getting some success against depression with a light box, but still find that I crave light, especially by the afternoon. My mood also tends to drop around then (3:00ish). Does this indicate I should use the light box longer in the morning? Would it help to use it again in the afternoon? Can I use the box, without sitting right in front of it, for general lighting, just to get more brightness in here?


Smart questions! Response in three parts:

  1. Often, the afternoon slump vanishes when the morning light dose is increased — so, yes, give that a try.
  2. Some patients find that they can largely prevent the afternoon slump with a supplementary light therapy session as soon as they feel the slump setting in. Often, a very brief session — for example, 10-15 minutes — suffices. Unlike morning light therapy, which should be repeated consistently every day, the supplementary session can be done “PRN” — as you need it. If there is a day without slumping, you can skip the session. If the slump starts at different times from day to day — say, 2:00 p.m. on one day, 3:30 p.m. on another — you can vary the time of afternoon light exposure. And if you are out of the house when the slump hits, you do not have to feel guilty about missing the session.
  3. No problem with leaving the light box on for extended periods during the day, as long as you are not sitting in direct proximity, risking overdose.