Block the light and sleep well: Evening blue light filtration as a part of cognitive behavioral therapy for insomnia

ABSTRACT

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, p = .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, p = .003, Cohen’s d = 0.95) and HAS score (t = 2.90, p = .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, p = .021, d = 0.73) and an increase of subjective total sleep time (t = −2.73, p = .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.

KEYWORDS:

• CBT-I
• insomnia
• sleep
• blue-light blocking
• chronotherapy
• anxiety
• depression

Acknowledgments

This study is a result of the research funded by the project Nr. LO1611 with financial support from the MEYS under the NPU I program. Further supported by project “PROGRES Q35”, 260388/SVV/2019 and GAUK 1064218.

Author contributions

M.Š. and K.J. conceived the original idea, planned and carried out the study, led CBT-I groups, performed statistical analyses and wrote the manuscript. E.F. analyzed actigraphic data and contributed to the interpretations of the results. J.K. supervised the project and provided guidance in writing the manuscript. All authors provided critical feedback and helped shaped the research.

Disclosure statement

The authors have no conflicts of interest to declare.

Statements of Ethics

This study had prior approval from the Ethical Committee of the National Institute of Mental Health, Klecany, Czech Republic. Written informed consent was obtained from each participant after an explanation of the nature and purpose of the study.