A reader asks:

How do the lights work?


Scientists are still investigating the precise mechanism that makes light therapy effective. Thus far, we believe that bright light works to reset the body’s internal clock, the “circadian rhythms” that control body temperature, hormone secretion and sleep patterns. Melatonin is a nighttime hormone that plays an important role in the body’s daily rhythms. The latest studies indicate that appropriately timed light exposure reduces melatonin “overshoot” into the early morning hours that might make people susceptible to depression.