Differences in devices, light spectrum,illuminance, and duration: Examining adverse effects of light Therapy

The integral role of light in physiological and psychological well-being is illustrated by the application of light therapy (LT) in treating mood disorders such as seasonal affective disorder and nonseasonal depression. LT has also successfully treated sleep disorders and disorders of circadian phase shifting. Potential efficacy in treating clinical symptoms of dementia, obsessive-compulsive disorder, attention deficit hyperactivity disorder, and eating disorders has also been observed. Due to the varied applications of LT, heterogeneous experimental methods have been used with variations in treatment length (ranging from one day to several weeks), light spectrum (blue, green, and full spectrum white light), dosage (30 minutes to 6 hours), and illuminance (2,500 - 10,000 lux). Additionally, trials have examined the effect of traditional phototherapeutic devices and more recently developed wearable light devices. The heterogeneity in methodologies and treatments has obscured the understanding of LT's adverse effects. Furthermore, few controlled trials have examined the incidence and tolerability of undesired side effects. The primary purpose of the current review is to evaluate side effect profiles of LT across phototherapeutic devices, light spectrums, durations, and illuminances.