Objective: The purpose of this study was to determine the effect of adjuvant light therapy with antipsychotic treatment in patients with delirium. Methods: Thirty-six patients were referred to the consulting psychiatry division of our hospital for a disturbance in consciousness. The patients were randomized to risperidone (n=16) or risperidone with light therapy (n=20). They were evaluated on Day 0 (baseline) and on Days 1 to 5 with the Delirium Rating Scale (DRS) and the Memorial Delirium Assessment Scale (MDAS). Sleep parameters were measured using a sleep log. Results: Mean DRS and MDAS scores decreased significantly over time in both treatment groups. Risperidone with light therapy group showed a significantly greater decrease in the DRS score than the risperidone-only group (F=2.87, P=.025), but the MDAS score was not significantly different between the two groups. There was a significant improvement in total sleep time (F=2.07, P=.037) and sleep efficiency (F=2.79, P=.029) in the risperidone with light therapy group than in the risperidone-only group. Conclusions: Our results indicate that risperidone with light therapy may be a helpful adjuvant treatment for patients with delirium. Adequately powered studies with a head-to-head comparison design are mandatory to confirm our findings. (C) 2012 Elsevier Inc. All rights reserved.