Effect of bright light therapy on depression in patients with schizophrenia: A pilot study

Objective: In this pilot study, we investigated the effects of bright light therapy on depression in schizophrenia using a quasi-experimental design involving random assignment. Methods: We included patients with schizophrenia who had stable psychiatric symptoms. Experimental group (n = 16) received light therapy while control group (n = 12) received only regular indoor light. The intervention was administered in the morning once a day for 50 min for three weeks. Scores of the Chinese version of the Calgary Depression Scale for Schizophrenia (CDSS-C), Chinese version of the Positive and Negative Syndrome Scale (PANSS-C), Clinical Global Impression-Schizophrenia Scale (CGI-SCH), and Stressful Life Event Scale (SLES) were measured at baseline (T0), immediately after 5th day of the intervention (T1), immediately after the 15th day of intervention (T2), and at the 14-day follow-up (T3). A generalized estimating equation (GEE) analysis was performed to analyse group × time interaction effects and effect of bright light therapy on depression. Results: Results indicated that bright light therapy alleviated depressive symptoms in patients with schizophrenia after controlling for internal or surgical diseases and disease duration (in years). However, the effect was not maintained two weeks after the treatment. Conclusion: These findings suggest that bright light therapy is a nonpharmacological adjunct treatment approach for patients with stable psychiatric symptoms.