A reader asks:

My MEQ recommended time (Automated Morningness-Eveningness Questionnaire on www.cet.org) for light for chronic non-seasonal depression is 6:30 a.m. I attended a party and did not get into bed until 2:00 a.m. The next day I did not get up until 10:30 a.m. I took my light treatment, but at that later time. I am under the impression that responsiveness declines as the time of the light exposure gets later. I used my light at the later hour and doubled my time of exposure. Should I have skipped that day since I missed my recommended time of 6:30 a.m.? Was it OK to use light later? Was it correct to lengthen my exposure time? Thank you for your service and care.


Good sleep hygiene–which is especially important for people with depression–mandates a consistent wake-up time, even when you go to bed late. Indeed, “sleeping in” can exacerbate depressive symptoms. In the real world, though, people will sometimes not be able to meet their early target time for light exposure. Light therapy later in the morning is better than skipping it altogether, but you should never use light therapy earlier than the MEQ-recommended time unless directed to do so (and monitored) by a clinician. Increasing light duration later in the morning makes intuitive and logical sense, but this has never been tested in clinical trials. Very interesting idea, but you’ll have to follow your nose with that strategy, and remain vigilant about overdose side effects such as headache and agitation