Bright light therapy (BLT), also known as phototherapy, is typically used to manage circadian rhythm disorders, however, new information suggests that BLT may treat depression symptoms as well. In a recent retrospective study by Wallace and colleagues, depression symptoms measured by the PHQ-9 were correlated to measures of bright light exposure from 6639 participants whose data was collected between 2011 and 2014 in the National Health and Nutrition Examination Survey. Specifically, these participants had valid data on light exposure and their sleep regularity index through wrist-worn actigraph monitors. Overall, male participants had higher TALT1000, a measure of bright light above lux threshold, and fewer depression symptoms than female participants. Initially, higher TALT1000 levels were associated with lower depression symptoms, but this was not the case after adjusting for the sleep regularity index (SRI). Instead, longer duration of bright light was associated with more regular sleep, and more regular sleep was associated with lower depression scores with lower odds of mild or more severe depression.
Reference:
Wallace DA et al. JAMA Netw Open. 2024;7(7):e2422810. Abstract.