O073 The effect of blue-enriched light in older adults with sleep disturbance on sleep and daytime performance: A randomised, placebo-controlled crossover trial

Abstract Introduction Light therapy is a non-pharmacological intervention for circadian and sleep disorders. However, there is limited evidence about the effect on electroencephalographic (EEG) sleep in older individuals with sleep disturbance. Methods Twelve participants (8 female; mean ± SD age, 65.6 ± 8.7 years) with self-reported poor sleep completed two randomly allocated 72-hour in-laboratory visits separated by 2 weeks. The intervention light condition consisted of blue-enriched light (melanopic EDI=843.6 lux) during the day and blue-depleted light (melanopic EDI=49.5 lux) 3-hours before lights out. The control light condition consisted of polychromatic light (melanopic EDI=215.8 lux) during the day and reduced light (melanopic EDI=60.8 lux) 3-hours before lights out. The primary outcome was wake after sleep onset (WASO), with secondary outcomes of sleep micro-architecture parameters (256-channel high-density EEG) and neurobehavioural performance. Results The intervention light did not improve WASO compared to the control (p=0.338) but there was a significant increase in N1 sleep (p=0.046). The only neurobehavioural difference was in Stroop text accuracy (2.2%, p=0.028). High-density EEG analysis showed the intervention light significantly increased sigma activity (12–16 Hz) in the frontal and parietal cortex during N2 sleep relative to control light (p=0.017). Conclusions Overall, blue-enriched light over three days did not improve EEG sleep (WASO) or neurobehavioural performances except for accuracy (Stroop) in older adults with sleep disturbance. Further research is required to determine the ideal intensity, spectral composition, duration and timing of blue-enriched lighting on objective sleep outcomes in individuals with poor sleep quality.