While carefully timed light exposure may address sleep problems associated with circadian rhythm disturbances, studies that examine light therapies in the context of sleep disorders have been largely lacking in measures of adherence and acceptability of these approaches. This is according to a systematic review article in Sleep Health.
Although light therapy is non-invasive, low in cost, and can exert a biological action similar to that of a drug, effects are observed most noticeably when used consistently over a long period of time. Additionally, the duration of each light therapy session must be 30 minutes or more, which can create a hefty time burden for the patient compared to taking a drug.
To evaluate the adherence and acceptability of light therapies, researchers from the United Kingdom examined 77 studies that used this approach in patients with intrinsic circadian rhythm sleep-wake disorders, dementia, psychotic disorders, affective disorders, and personality disorders. Approximately half of these studies featured a control group. Interventions in these studies included the use of light boxes, natural light, visors, light avoidance, and blue-blocking glasses.
The use of light boxes to deliver bright light to participants was the most common intervention in 47 studies. Duration and dose of delivered light varied across studies. Also, the setting in which light therapy was applied in these studies (ie, laboratory vs home) may reduce the generalizability of the research findings. In regard to expectations of treatment, some studies suggested that participants expected only a moderate effect of light therapy.
And while the overall acceptability of the studied light therapies was high, the acceptability measure was often obtained from questionnaires that may or may not have been anonymous. This could have presented some level of bias in the study design. In addition, some studies reported that participants considered the time it took to receive therapies was not ideal, yet 6 studies included a high proportion of participants who stated they were going to continue treatment with either the study device or a light device they purchased outside the clinical setting.
In 52 studies, the mean attrition rate was low (17%). A mean 5% attrition rate was found in 25 studies that itemized attrition by reasons. Self-reported measures of adherence were high in studies that reported adherence.
A limitation of this review included the variability among studies in terms of diagnostic samples and intervention types.
Based on their findings, the investigators wrote that enhanced “measurement and reporting of acceptability and adherence-related factors may help to optimize adherence, reduce burden, and improve user experiences.”
Faulkner SM, Dijk DJ, Drake RJ, Bee PE. Adherence and acceptability of light therapies to improve sleep in intrinsic circadian rhythm sleep disorders and neuropsychiatric illness: a systematic review [published online March 12, 2020]. Sleep Health. doi: 10.1016/j.sleh.2020.01.014.