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Not much evidence exists concerning the effects on sleep and mood of transcranial bright light. In this study, 50 students, all with wake-up time 9:00 a.m. or later in weekends/free days, participated in a double-blind placebo-controlled experiment comparing the effects of bright light ( n = 27; 8.0 lm) and placebo ( n = 23; 0.1 lm). Data collection consisted of sleep assessment, with both sleep diaries and actigraphy. In addition, the Fatigue Severity Scale and the Profile of Mood States (POMS) were administered. Following 1 week of baseline recording, the therapy was initiated, aiming to phase advance the sleep-wake period. The therapy lasted for 2 weeks and consisted of gradually advancing daily light exposure of 12 min' transcranial bright light. Subjects in the two conditions did not change differently from baseline to post-treatment on any sleep parameters. A significant condition × time interaction was found for one of six subscales (vigor-activity) of the POMS, suggesting a more favorable development from baseline to post-treatment in the placebo compared to the bright light condition. No differences in terms of side-effects were reported between conditions. It is concluded that transcranial bright light, at times where conventional light therapy has phase-advancing properties, did not influence any sleep parameters differently than placebo. Transcranial bright light was associated with a less favorable development from baseline to post-treatment on one mood parameter compared to placebo. [ABSTRACT FROM AUTHOR]

Background Bright light treatment is effective for seasonal affective disorder (SAD), although the mechanisms of action are still unknown. We investigated whether transcranial bright light via the ear canals has an antidepressant effect in the treatment of SAD. Methods During the four-week study period, 89 patients (67 females; 22 males, aged 22-65, mean ± SD age: 43.2 ± 10.9 years) suffering from SAD were randomized to receive a 12-min daily dose of photic energy of one of three intensities (1 lumen/0.72 mW/cm2; 4 lumens/2.881 mW/cm2; 9 lumens/6.482 mW/cm2) via the ear canals. The light was produced using lightemitting diodes. The severity of depressive symptoms was assessed with the Hamilton Depression Rating Scale - Seasonal Affective Disorder (SIGH-SAD), the Hamilton Anxiety Rating Scale (HAMA), and the Beck Depression Inventory (BDI). Cognitive performance was measured by the Trail Making Test (TMT). The within-group and between-group changes in these variables throughout the study were analysed with a repeated measures analysis of variance (ANOVA), whereas gender differences at baseline within the light groups were analysed using Student's t-tests. Results Patients in all three groups showed significant decreases in their BDI, HAMA, and SIGHSAD scores. Response rates, i.e., an at least 50% decrease of symptoms as measured by the BDI, were 74%-79% in the three treatment groups. Corresponding variations for the SIGHSAD and the HAMA were 35-45% and 47-62%, respectively. No intensity-based doseresponse relationships in the improvement of anxiety and depressive symptoms or cognitive performance between treatment groups were observed. Approximately one in four patients experienced mild adverse effects, of which the most common were headache, insomnia, and nausea. Conclusions These results suggests that transcranial bright light treatment may have antidepressant and anxiolytic effect in SAD patients, as both self- and psychiatrist-rated depressive and anxiety symptoms decreased in all treatment groups. These improvements are comparable to findings of earlier bright light studies that used conventional devices. The lack of dose response may be due to a saturation effect above a certain light intensity threshold. Further studies on the effects of transcranial bright light with an adequate placebo condition are needed. Trial registration NCT01293409, ClinicalTrials.gov [ABSTRACT FROM AUTHOR]