Figueiro and colleagues evaluated how people with Alzheimer’s disease and related dementias are affected by lighting. The participants in their study were individuals with moderate to severe dementia and sleep disturbance. The researchers report that “This study explored the effects of a circadian-effective lighting intervention. . . Following a crossover, placebo-controlled design, 3 different lighting modes were used to deliver high levels of circadian stimulus to the participants’ eyes for two 8-week intervention periods in a counter balanced order with a 4-week washout between the study’s 2 conditions (dim light control vs. active intervention). Actigraphy and questionnaire data were collected over 7-day assessment periods that preceded (baseline weeks 1 and 9) and concluded (post-intervention week 9 and 22) the intervention periods. . . . Under the active condition, sleep duration significantly . . . increased and sleep start time significantly . . . advanced after the intervention compared to baseline. . . . a circadian-effective lighting intervention delivering bright days and dark nights improves measures of sleep and mood in dementia patients living in controlled environments.”
Mariana Figueiro, David Pedler, Barbara Plitnick, Erick Zecena, and Sophie Leahy. 2023. “Tailored Lighting Interbention (TLI) for Improving Sleep-Wake Cycles in Older Adults Living with Dementia.” Frontiers in Psychology, vol. 14, https://doi.org/10.3389/fphys.2023.1290678