Light up: an intervention study of the effect of environmental dynamic lighting on sleep–wake rhythm, mood and behaviour in older adults with intellectual disabilities

Background Evidence‐based interventions to improve the sleep–wake rhythm, mood and behaviour in older adults with intellectual disabilities (ID) are limited. Increasing light exposure has been shown to be effective in improving the sleep–wake rhythm, mood, and behaviour in other populations. The current study investigates the effect of installing environmental dynamic lighting in common living rooms of care facilities on sleep–wake rhythm, mood, and behaviour in older adults with ID. Methods A non‐randomised, non‐concurrent, multiple baseline study was performed from October 2017 to May 2018. Fifty‐four participants [mean (SD) age of 63.42 (8.6) years, 65% female] in six care facilities were included. All participants had three baseline measurements (Weeks 1, 5 and 9). Dynamic lighting was installed in Week 10, after which three intervention measurements took place (Weeks 12, 17 and 24). Sleep characteristics and the sleep–wake rhythm were assessed using actigraphy (GENEActiv). Mood was measured with the Anxiety, Depression and Mood Scale (ADAMS) and behaviour with the Aberrant Behaviour Checklist (ABC). Results Mixed‐effect regression analysis showed a worsening of the primary outcome interdaily stability (P = 0.001). This could be attributed to one care facility, whereas interdaily stability did not change in the other care facilities (P = 0.74). Dynamic lighting led to earlier mid‐sleep (P = 0.003) and sleep onset (P