21 Nevertheless, today there is sound evidence showing that antidepressant effects of light in SAD are real biological treatment effects.16,20,22 Dose Earlier studies have mostly used light intensities of 2500 lux. This is much more than the typical indoor illumination, ranging from 100 lux in average rooms to about 500 lux in brightly illuminated ones. Outdoor light intensities #inhibitors keyword# greatly vary with weather conditions ranging from
about 2000 lux on a rainy winter day to 10 000 lux or more (usually 50 000 to 300 000 lux) in direct sunshine. Today, light treatment with intensity of 10 000 lux has become clinical standard. One great advantage of higher intensity light is that Inhibitors,research,lifescience,medical it allows for shorter exposure times. Current clinical guidelines recommend beginning treatment with 10 000 lux for 30 min in the morning.23 Nevertheless, intensities of 2500 lux have shown to have antidepressant effects when applied for 2 h daily. Timing A further finding that emerged from BLT studies is the superiority of morning light over light administered in the evening.16,20,22 By further refining
timing Inhibitors,research,lifescience,medical of light administration in relationship to the position of the circadian phase, Terman and coworkers achieved remission rates up to 80% in selected patient populations.5 They were able to show that response to BLT critically depends on time of delivery relative to the position of the circadian phase as determined by the onset of melatonin secretion in the evening (dim-light melatonin onset). The study suggests that the ideal therapy time is around 8.5 h after melatonin onset. Although the superiority Inhibitors,research,lifescience,medical of morning light in the majority of patients with SAD had been demonstrated before,16,20,22 Terman and colleagues showed that, for clinical purposes, circadian phase position can simply and reliably be determined
by administration of a modified version Home-Qst-berg morningness-eveningness scale.24 The authors also provide an online-questionnaire25 together with recommendations for individually optimized light therapy Inhibitors,research,lifescience,medical timing as based on morningness-eveningness or individual circadian phase position. In summary, now there is sufficient evidence that light administered Cell press in the early morning is superior to evening light. Dawn stimulation Many patients with SAD experience markedly increased duration of sleep during the winter months.1,4,26 Usually, most of these patients have to force themselves out of bed during the weekdays despite feeling excessively drowsy. Dawn stimulation is a form of light therapy involving gradually increasing bedside light in the morning before awakening.27 Dawn stimulation has shown to improve symptoms of SAD compared with placebo light signals.28,29 In addition, dawn stimulation appears to be effective in ameliorating the difficulty awakening and morning drowsiness in SAD.