Therapeutic prospects of bright light therapy in addictive disorders: a scoping review

Bright light therapy (BLT) is now established as an evidence-based treatment for several psychiatric and sleep disorders, with robust efficacy in seasonal affective disorder, non-seasonal, unipolar, and bipolar depression, insomnia and circadian rhythm sleep-wake disorders, including Delayed Sleep-Wake Phase Disorder. BLT-related mechanisms are multifactorial, combining circadian phase-shifting effects, stabilization of the sleep-wake cycle, improved homeostatic sleep pressure, and modulation of monoaminergic pathways. Beyond these effects, recent translational studies suggest that BLT also modulates the brain reward system through circadian-dopaminergic interactions, providing a neurobiological rationale for its use in disorders where motivation, reward sensitivity, and compulsive behaviors are disrupted. Despite these advances, BLT has been largely neglected in the field of addictive disorders, even though circadian disruption, sleep disturbances, and mood instability are central clinical features of addiction. This scoping review explores the therapeutic prospects of BLT in addictive disorders. We first summarize the established evidence supporting BLT for mood and sleep disorders, which provides a strong translational basis. We then discuss three potential applications in addiction: (1) alleviating comorbid or subthreshold mood and anxiety symptoms, which are highly prevalent and disabling in substance use and behavioral addictions; (2) improving sleep and circadian regulation, frequently impaired in these populations and closely linked to relapse vulnerability; and (3) directly modulating the reward system and core addictive behaviors. In conclusion, BLT offers many potential benefits for patients with addictive disorders. Well-designed trials are now needed to confirm efficacy, refine protocols, and integrate BLT into addiction care.