BACKGROUND: Daylight entrains the central circadian pacemaker to the 24-hour day and is crucial for optimal alertness and sleep-quality. Rehabilitation patients tend to lack exposure to sufficient natural light.

OBJECTIVE: Installed diurnal naturalistic light may reduce the known disrupted sleep quality and fatigue seen in post stroke patients.

METHODS: Stroke patients were randomized to either an intervention rehabilitation unit (IU) equipped with naturalistic lighting (artificial sunlight spectrum) or to a control rehabilitation unit (CU) with standard indoor lighting. At inclusion and discharge, fatigue and subjective sleep quality were measured.

RESULTS: Ninety stroke patients were included between May 2014, and June 2015. At discharge, patients from the IU experienced less fatigue than the CU patients, based on the Multidimensional Fatigue Inventory questionnaire general (IU, n = 28; CU, n = 30; diff - 20.6%, 95% confidence interval (CI) [- 35.0%; - 3.0%]; P = 0.025) and the Rested Statement (IU, n = 28; CU, n = 30; diff + 41.6%, 95% CI [+4.6%; +91.8%]; P =  0.025). No differences were detected between groups in sleepiness or subjective sleep quality by the Pittsburgh Sleep Quality Index.

CONCLUSIONS: Fatigue was significantly reduced in rehabilitation patients exposed to naturalistic lighting during admission.