Block the light and sleep well: Evening blue light filtration as a part of cognitive behavioral therapy for insomnia.
Chronobiol Int. 2020 02 ;37(2):248-259. Epub 2019 Nov 22. PMID: 31752544
The objective of the present study was to assess the effect of combining CBT-I with wearing blue-light blocking glasses 90 min prior to bedtime on subjective and objective sleep parameters and daily symptoms (anxiety, depression, hyperarousal). Thirty patients (mean age 48.1± 16.13 years, range 21-71, 15 men/15 women) completed a CBT-I group therapy program, with groups randomly assigned to either"active"(blue-light filtering glasses) condition or"placebo"(glasses without filtering properties) condition. Patients were continually monitored by wristwatch actigraphy, kept their sleep diaries and completed a standard questionnaire battery at admission and after the end of the program. Statistical analyses showed a greater reduction of BAI score in"active"(4.33± 4.58) versus"placebo"(-0.92± 3.68) groups of patients [F = 6.389,= .019, Cohen's d = 1.26] and significant prolongation of subjective total sleep time in"active"(-36.88± 48.68 min.) versus"placebo"(7.04± 47.50 min.) [F = 8.56, p<.01, d = 0.91] group. When pre- and post-treatment results were compared in both groups separately, using paired-samples t-tests, significant differences were observed also in the active group for BDI-II score (t = 3.66,= .003, Cohen's d = 0.95) and HAS score (t = 2.90,= .012, Cohen's d = 0.75). No significant differences were found in the placebo group. In active group, there was also a significant reduction of subjective sleep latency (t = 2.65,= .021, d = 0.73) and an increase of subjective total sleep time (t = -2.73,= .018, d = -0.76) without change in objective sleep duration which was significantly shortened in the placebo group. We provide further evidence that blocking short-wavelength light in the evening hours may be beneficial for patients suffering from insomnia.