Too noisy, too dark: sleep environment at a typical stroke unit

Sleep-wake disorders are common after stroke and negatively affect stroke outcome. Environmental factors such as noise and light exposure can perturb sleep quality and destabilise circadian rhythm. This study aimed to quantify light and noise exposure of hospitalised patients in a stroke unit and assessed compliance with recommended guidelines.

Between July and August 2021, noise and light levels were measured in the former stroke unit of the Inselspital Bern. Noise exposure was assessed via the equivalent continuous A-weighted sound pressure level (LAeq), light exposure was assessed using melanopic equivalent daylight illuminance.

World Health Organization recommended noise levels (30 dB at night and 35 dB during the day) were constantly exceeded. Door beds were significantly noisier than window beds during evenings (53 ± 3.3 dB vs 48.6 ± 3.5 dB) and during nighttime (43.4 ± 4.0 dB vs 39.5 ± 4.5 dB). Minimal daytime illuminance of 250 lx melanopic equivalent daylight illuminance was hardly ever reached at door beds (15 ± 30 min) but was reached for about 3 h throughout the day at window beds (186 ± 108 min). The highest quantity of illuminance was reached during late evening hours (18-22 h) for both window and door beds rather than in the mornings (6-10 h).

These observations suggest that the setting of monitored stroke units is unfavourable for sleep because of insufficient light and excessive noise exposure. Further studies are needed to confirm this observation and assess the associated effects on sleep-wake functions and stroke outcome.