Persistent daytime symptoms of sleepiness in individuals with obstructive sleep apnea (OSA) who are using Continuous Positive Airway Pressure (CPAP) are associated with adverse long term medical and functional outcomes. Supplementary exposure to bright light has beneficial effects on sleep quality and daytime vigilance in healthy individuals and it has been increasingly applied in a variety of sleep and neuropsychiatric conditions. This study will explore the role of Bright Light Therapy (BLT), a well-established non-pharmacological intervention for circadian disturbances, for the treatment of residual daytime symptoms of OSA which do not respond to CPAP. BLT will be delivered via therapy glasses in a cross-over design, where each participant will be exposed to active treatment and sham treatment (4 weeks in each arm) in a randomized order. The hypothesis is that participants will demonstrate improvements in the variables of interest during the four-week active treatment portion of the eight-week crossover study, compared to the four-week sham treatment portion.