Light therapy for obsessive-compulsive disorder: A circadian medicine approach - PROJECT SUMMARY/ABSTRACT Obsessive-compulsive disorder (OCD) is characterized by intrusive, distressing thoughts (i.e., obsessions) and repetitive behaviors (i.e., compulsions) and is associated with significant functional impairment. Despite established first-line treatments, non-remission and relapse rates following treatment are high (e.g., ~50%), suggesting the existence of unidentified and untreated mechanisms in OCD. Prior work linking delayed circadian rhythms to OCD suggests this may be one such mechanism and represent a novel treatment target. Light therapy is a behavioral treatment that advances circadian rhythms and has been shown to be effective for reducing symptoms of disorders that are phenomenologically similar to OCD (i.e., posttraumatic stress disorder; Tourette’s disorder). Light is the primary zeitgeber, or environmental time cue, of human circadian rhythms, and light exposure also has direct effects on brain regions implicated in psychopathology. However, no study to date has tested the efficacy of light therapy for OCD. This project will address this gap in the literature by comparing the efficacy of light therapy (n=20) versus placebo light therapy (n=20) for OCD symptom reduction in adults with OCD+delayed bedtimes and examining change in circadian phase as a mechanism. We will also examine photic sensitivity and habitual light exposure patterns in adults with OCD+delayed bedtimes compared to healthy controls (n=25). Participants will complete 2 weeks of baseline sleep and OCD symptom monitoring followed by a baseline dim light melatonin onset (DLMO) and photic sensitivity assessment. Participants will then be randomly assigned to the active or placebo treatment condition and complete 5 weeks of treatment. OCD symptoms and DLMO will be reassessed at the end of treatment. We will examine whether OCD symptoms improve in the active treatment condition compared to the placebo treatment condition and whether change in symptoms is associated with advanced circadian phase. We will also examine whether adults with OCD+delayed bedtimes exhibit heightened light sensitivity and maladaptive habitual light exposure patterns (lower daytime, higher evening light). Results from this study will inform whether delayed circadian rhythms can be targeted for OCD symptom reduction. Through this project, I will complete transdisciplinary training in clinical trials in circadian medicine, advanced methods in light measurement and photic sensitivity, longitudinal modeling, and professional development, service, and scientific writing. This project will also provide me with preliminary data to be competitive for an R01 to facilitate my transition to independence.
