USING BLUE LIGHT THERAPY TO FACILITATE RECOVERY OF SLEEP AND PSYCHOLOGICAL FUNCTIONING IN PTSD

Abstract Introduction Sleep problems are often described as the “hallmark symptoms” of post-traumatic stress disorder (PTSD). Patients with PTSD show numerous disruptions of emotional functioning. Experimental evidence has shown that the ability to retain extinction memories following fear conditioning is impaired in people with PTSD. Because of the key role of sleep in memory consolidation and emotional regulation, we hypothesized that regulating sleep and circadian rhythms with morning blue-wavelength light therapy would facilitate emotional recovery and the ability to retain extinction memories. Methods Eighty-four individuals with PTSD (56 female; Age=31.38, SD=8.9) underwent a well-validated fear conditioning and extinction protocol and were then randomly assigned to receive either 6-weeks of BLUE (469 nm; n=44) or placebo AMBER (578 nm; n=40) morning light therapy for 30-minutes daily. Participants returned to undergo post-treatment extinction recall when exposed to the same previously conditioned stimuli, and a functional magnetic resonance imaging (fMRI) while the same images were presented. Participants also completed a variety of emotional and mental health outcome measures and wore an actigraph to measure sleep over the 6-weeks. Results There was a significant interaction between light condition and time in bed and total sleep time (p<.05) indicating significant increases in sleep with blue versus amber light over treatment. Additionally, declines in symptoms of PTSD on the Clinician Administered PTSD Scale (CAPS-5) correlated with improvements in sleep for the blue, but not the amber light, group (all p-values <.05). During the fear conditioning and extinction paradigm, blue light was associated with significantly greater extinction recall compared to the amber light condition (p=.05). Finally, blue light resulted in decreased fMRI activation within the right amygdala and increased activation within the ventromedial prefrontal cortex to the previously feared and extinguished stimuli. Conclusion Blue light treatment was more effective than amber placebo at increasing sleep quantity, shifting circadian bedtime, reducing PTSD symptom severity, facilitating the retention of extinction memories, and reducing neural fear responses to previously feared stimuli. We suggest that improvements in sleep led to greater consolidation of extinction memories. These findings suggest that blue light treatment may facilitate treatment gains by improving sleep. Support (If Any)