A common question regarding bright light therapy (BLT): when do I administer the light?
BLT is most effective when administered for 30 minutes in the early morning. The optimal time for light exposure is 8.5 hours after the onset of melatonin secretion the prior night (Lam & Tam, 2009). Use the Morningness-Eveningness Questionnaire (MEQ) to estimate each patient’s ideal time for BLT. Questions include what time do you get up in the morning, do you require an alarm clock, how alert do you feel after you wake up? A copy of the MEQ can be found here, and scoring parameters are included below. An individuals score determines the approximate time of melatonin secretion and the corresponding appropriate time for BLT. Although the psychometric properties of the MEQ have not yet been confirmed, this test is recommended by experts in the field of chronotheraputics (Golden et al., 2005).
Golden, R. N., Gaynes, B. N., Ekstrom, R. D., Hamer, R.M., Jacobsen, F. M., Suppes, T., Wisner, K. L., & Nemeroff, C. B. (2005). The efficacy of light therapy in the treatment of mood disorders: A review and meta-analysis of the evidence. Am J Psychiatry, 162, 656-662. Retrieved from http://www.chronobiology.ch/wp-content/uploads/2013/04/Golden-AJP-April-2005.pdf
Lam, R. W., & Tam, E. M. (2009). A clinician’s guide to using light therapy. New York, NY: Cambridge University Press.