The current study aims to compare the efficacy of blue light, bright light and dim light in the treatment of with nonseasonal major depression disorder(MDD) in adults. 162 patients with nonseasonal MDD will be randomized into three groups (i.e. blue light, bright light or dim light). The treatment will be performed five times a week for the first two weeks. And for the next 2 weeks, the treatment for patients will be undertook three times a week. There will be 16 times in total. The investigators will assess nonseasonal MDD'symptom severity in the baseline, 1 week,2 week, 4 week,6 week and 8 week. Through the study, 17-item Hamilton Depression Rating Scale (HAMD17),14-item Hamilton Anxiety Rating Scale (HAMA14),Quick Inventory of Depressive Symptoms, Self-Rated version (QIDS-SR)，Pittsburgh sleep quality index (PSQI) , Clinical Global Impression scale(CGI), Quality of Life, Enjoyment and Satisfaction Questionnaire (Q-LES-Q),Morningness-Eveningness Questionnaire (MEQ),Repeatable Battery for the Assessment of Neuropsychological Status(RBANS),subjective fatigue symptom scale and semantic differential scale will be obtained. The patients will also get individual's data of heart rate and blood pressure.
