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.
M N Böhmer, A Oppewal, M J Valstar and 3 others
PMID 36004439WHAT IT FOUND
Installing dynamic lighting in living rooms improved mood and reduced depressive symptoms in older adults with intellectual disabilities.
However, it did not stabilise their sleep-wake rhythm as hypothesised, and the effect on sleep onset was minor.
Key findings
01Depressive symptoms decreased significantly, with the average score dropping by 3.42 points and the percentage of participants above the clinical cut-off falling from 23% to 9.8%.
02The primary hypothesis was not met: dynamic lighting did not stabilise the sleep-wake rhythm. An initial finding of worsened stability was attributed to a single care facility, and excluding it showed no effect.
03Behavioural measures improved, with significant reductions in hyperactivity, irritability, lethargy and social avoidance, though there was no effect on anxiety.
STILL TO COME
How it was doneWhat they foundWhat it means for OTs
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What it does not show
The study was non-randomised and lacked a concurrent control group, relying on a multiple baseline design which is less robust than an RCT. Mood and behaviour were rated by professional caregivers who were also exposed to the lighting, introducing potential bias if their own mood or perception changed. The sample was relatively mobile and had mild-to-moderate intellectual disabilities, so results may not generalise to those with severe or profound disabilities. The study took place around the winter holidays, a period that can be stressful for this population, which might have confounded the improvements seen during the intervention phase. Personal light exposure data was unreliable due to high missingness from incorrect sensor wear.
Declared interests
The study was supported financially and organisationally by Middin, the care organisation where the study took place. The authors declared no conflicts of interest, and stated that the lighting manufacturer did not sponsor the project or influence the design, analysis, or writing.
The easy way to misread this
Do not assume this lighting intervention will improve sleep quality or regulate sleep-wake rhythms in your patients. The study found no significant benefit for the primary sleep outcomes, and the positive mood effects were not linked to improved sleep stability.