The effect of bright light therapy on depressive symptoms in adults with intellectual disabilities: Results of a multicentre randomized controlled trial

Background: Although a large number of adults with intellectual disabilities have depressive symptoms, non-pharmacological treatments are scarce. The present authors investigated whether bright light therapy (BLT) is effective in decreasing depressive symptoms compared to care as usual. Methods: This multicentre randomized controlled trial consisted of three study groups (10,000 lux BLT, dim light BLT and a no-BLT group). Participants received BLT for 30 min in the morning (14 consecutive days), additional to their regular care. Primary outcome was as follows: depressive symptoms measured with the ADAMS Depressive Mood subscale 1 week after the end of BLT (same time period in the noBLT group). Results: Forty-one participants were included in our trial. In both BLT groups, a significant decrease in depressive symptoms was seen. No significant differences were found between 10,000 lux BLT and no-BLT (p = .199) and no significant differences between dim light BLT and no-BLT (p = .451). A minimum amount of side effects and no adverse events were reported. Conclusions: In both BLT interventions, a decrease in depressive symptoms was seen. With 10,000 lux BLT, depressive symptoms decreased even below the clinical cut-off point, which makes BLT a promising intervention for clinical practice.

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