0924 A 4-Week Morning Light Treatment Reduces Amygdala Reactivity and Clinical Symptoms in People with Traumatic Stress

Abstract Introduction Trauma exposure can result in anxiety, depression, and posttraumatic stress disorder. Although psychotherapies and pharmacotherapies exist for traumatic stress, many individuals remain symptomatic. New interventions for traumatic stress that target underlying mechanisms (e.g. amygdala reactivity) and are safe and acceptable are needed. Here we report on a randomized clinical trial in which we tested 3 doses of a 4-week morning light treatment in people with traumatic stress. Methods Forty-two adults (32 females, 19-57 years) with traumatic stress (experienced a DSM-5 Criterion A trauma, DASS score >22, and ≥ 2 moderate hyperarousal symptoms) completed a 5-week protocol. In the first week each participant slept at home, ad lib, on their usual sleep schedule. Thereafter, they followed a fixed sleep schedule and a 4-week morning light treatment (randomized to 15 mins, 30 mins or 60 mins of light each morning). Amygdala reactivity (emotional faces task - fMRI), clinician rated symptoms (PSSI, HAM-A, HAM-D) and self-reported symptoms (PCL-5, DASS) were assessed at baseline, and after 4 weeks of morning light treatment. Results Amygdala reactivity (left and right, negative faces vs shapes) in all 3 morning light groups significantly reduced during treatment (ps< 0.04). The 30 and 60 min groups had larger effect sizes in the reduction in amygdala reactivity than the 15 min group (ds=0.33-0.67 vs ds=0.11-0.16). All clinical symptoms significantly reduced during the treatment (ps< 0.001). There was a trend for self-reported depression, anxiety and stress symptoms to decline the most in the 60 min group (DASS d=1.35, p=0.06). Similarly, clinician rated depressive symptoms declined the most in the 60 min group (HAM-D d=2.25, p=0.03). No significant side effects were reported. Treatment satisfaction (average 7/10) and adherence (average 91%) were similar between groups (ps>0.05). Conclusion Results suggest that a 4-week morning light treatment can reduce amygdala reactivity and improve clinical symptoms in people with traumatic stress. The longest duration of morning light treatment, 60 minutes, produced some of the largest reductions in self-reported depression, anxiety and stress symptoms, and in clinician rated depressive symptoms. Morning light treatment should be further explored as a feasible, acceptable and effective adjunctive non-pharmacological treatment for traumatic stress. Support (if any) R61 MH117157