Background: Dysregulation of the endogenous biological clock is central to the pathophysiology of mania. The strongest time-giving signal is short wavelength (blue) light to which intrinsically photosensitive retinal ganglion cells containing the pigment melanopsin are primarily sensitive. Blocking blue light in the evening produces a physiological darkness condition.
Methods: In a randomized controlled trial with blinded raters conducted in a large academic hospital (Ontario, Canada), inpatients with mania were randomized to adjunctive blue-blocking glasses or lightly tinted glasses until discharge or up to two weeks. The primary outcome, improvement in manic symptoms on the Young Mania Rating Scale (YMRS), was assessed as a group by time interaction using linear mixed models. Secondary outcomes included differences in medication use. Registered on clinicaltrials.gov: NCT05206747.
Results: A total of 42 participants were randomized to blue-blocking glasses (n = 20) or lightly tinted glasses (n = 22). Those prescribed blue-blocking glasses did not show significant improvements in the YMRS relative to those with control lenses (difference of change in estimated marginal means at week 2 favoring control group by 2.1 points on YMRS, group ∗ time interaction p = 0.93). Average antipsychotic dose (7.2 vs. 7.1 mg/day risperidone equivalents, p = 0.29) and benzodiazepine dose (0.7 mg/day lorazepam equivalents for both groups, p = 0.67) did not differ significantly between groups. There were no differences in other secondary outcomes.
Conclusions: Despite the biological plausibility of the intervention and promising prior studies, blue-blocking glasses were not superior to lightly tinted lenses in their effects of manic symptoms in this randomized controlled trial in an inpatient setting.
Keywords: Bipolar disorder; Blue blocking glasses; Chronotherapy; Dark therapy; Mania; Randomized controlled trial.
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