A controlled trial of timed bright light and negative air ionization for treatment of winter depression. Arch Gen Psychiatry 55:875–882

Background: Artificial bright light presents a promising nonpharmacological treatment for seasonal affective disor-der. Past studies, however, have lacked adequate placebo controls or sufficient power to detect group differences. The importance of time of day of treatment—specifically, morn-ing light superiority—has remained controversial. Methods:Thisstudyusedamorning 3 eveninglightcross-overdesignbalancedbyparallel-groupcontrols, inaddition toanonphoticcontrol,negativeair ionization.Subjectswith seasonalaffectivedisorder(N = 158)wererandomlyassigned to 6 groups for 2 consecutive treatment periods, each 10 to 14days.Light treatmentsequencesweremorning-evening, evening-morning,morning-morning,andevening-evenin