A reader asks:

 I started using a 10,000 lux light box last fall with dramatically positive results. Because I felt better during the winter with the light box than I usually do during May, June and July, I concluded that I would benefit from year-round use. Given the longer hours of daylight now (May) can I be getting too much light?


You will know if you are getting too much light if you become speedy, hyper, or high to the point that you’re slightly out of control (“hypomanic”) . . . or if you start having insomnia with unreasonably early waking. In most cases of SAD, patients sense correctly that they no longer need supplementary light exposure by early May. That said, however, new investigations are pointing to year-round use of light therapy by patients with chronic (non-seasonal) depression. In certain circumstances, then, this strategy can be useful.