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Question In patients with seasonal affective disorder (SAD), is morning or evening light more effective in reducing symptoms?
Randomised, crossover trial with follow up to end of treatment.
Sleep and Mood Disorders Laboratory in Portland, Oregon, USA.
56 patients between 25 and 61 years of age who were recruited through media and referrals from health professionals with a DSM-III-R diagnosis of SAD and a score of ≥20 on the Structured Interview Guide for the Hamilton Depression Rating Scale-Seasonal Affective Disorder Version (SIGH-SAD). Exclusion criteria included poor physical health, ideas or attempts of suicide, use of psychotropic medication, and other Axis I-III disorders. 5 patients did not complete the study. 52 matched controls with no notable medical or psychiatric problems also participated. 3 controls did not complete the study.
After a baseline assessment period patients were allocated to bright light at either 6–8 am or 7–9 pm for 2 weeks. After 1 week of withdrawal from light treatment, patients were crossed over to the alternate light schedule.
Main outcome measures
Symptom severity assessed using the SIGH-SAD and dim light melatonin onsets.
During the course of treatment, SIGH-SAD scores for patients in the morning light group decreased twice as much as scores for patients in the evening light group. Remission (defined as ≥50% decrease in SIGH-SAD ratings to a score after treatment of ≤14) occurred in 19 patients receiving morning light compared with 3 patients receiving evening light (table). Morning light advanced the dim light melatonin onset and evening light delayed it in both patients and control participants. Patients were delayed compared with control participants at all assessment points of the study.
Bright morning light reduced depressive symptoms in patients with seasonal affective disorder.
Sources of funding: Public Health Service, Bethesda, MD, and the National Alliance for Research on Schizophrenia and Depression, Chicago, IL.
For correspondence: Dr A J Lewy, Sleep and Mood Disorders Laboratory, Department of Psychiatry, L-469, Oregon Health Sciences University, 3181 SW Sam Jackson Park Road, Portland, OR 97201-3098, USA. Fax +1 503 494 5329.
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