Effects of a Combination of Wooden Interior and Indirect Lighting in the Bedroom on Improving Sleep Quality and Attenuating Fatigue

Abstract

Objective: We conducted a clinical study to investigate the effects of a combination of wooden interior and indirect lighting in the bedroom on improving sleep quality and attenuating fatigue. Design: Eleven healthy male subjects, whose Pittsburgh Sleep Quality Index (PSQI) scores were ≥ 6, participated in a 3-way crossover trial. Subjects rested from 21:00 to 22:00 under a combination of wooden interior and indirect lighting, indirect lighting, or direct lighting, went to bed at 22:00, and awoke at 6:00. We evaluated sleep quality by the St. Mary's Hospital Sleep Questionnaire (SMHSQ), autonomic nervous function by the Active Tracer, sleepiness and fatigue sensation by the Visual Analogue Scale (VAS), and performance by the Advanced Trail Making Test (ATMT). Results: The combination of wooden interior and indirect lighting improved early morning awakening, nocturnal awakening, and satisfaction with sleep according to the SMHSQ, activated the parasympathetic nerve system at bedtime according to the Active Tracer, and attenuated sleepiness and fatigue sensation at the time of awakening according to the VAS; moreover, it improved work performance according to the ATMT. Conclusion: These results show that the combination of wooden interior and indirect lighting produces a suitable bedroom environment that improves sleep quality and attenuates fatigue.