The Impact of Dynamic Lighting on Sleep Timing and Duration for Hospitalised Patients.

Poor sleep is common in hospitalised patients due to multiple factors, including disruption of the circadian rhythm. Few studies have examined programmable artificial lighting systems in hospital patient rooms, and few have achieved meaningful improvement in sleep. We sought to determine how novel dynamic lighting affects sleep timing and duration compared to standard hospital lighting. Patients were admitted to rooms on a cardiology unit with customised intervention or standard lighting. The lighting system delivered blue-enriched light during the day, a melanopic stimulus twice daily and blue-depleted light in the evening. Sleep/wake probability was measured in 30-s epochs using mattress sensors to capture sleep timing and nocturnal sleep duration. Subjective sleep duration and alertness were assessed with sleep diaries and the Karolinska Sleepiness Scale (KSS), respectively. A total of 87 patients were enrolled. Subjects experiencing customised lighting demonstrated significantly advanced rest/wake activity phase by 160 min and overall greater sleep probability. Overnight sleep duration (11 p.m.-7 a.m.) was 66 min greater in the lighting condition (266 vs. 200 min, p < 0.05). Patients in the intervention group reported higher levels of alertness during the morning (KSS score 3.8 vs. 4.9, p = 0.01) and evening (5.4 vs. 7.1, p = 0.01). A lighting system programmed to entrain the circadian rhythm and provide a daytime melanopic stimulus on a hospital unit was associated with advanced circadian phase, increased nocturnal sleep duration and increased perceived morning and evening alertness. These results suggest that dynamic lighting systems have the potential to improve sleep for hospitalised patients.