Sleep disturbances in Lewy body dementia: A systematic review

BACKGROUND: Lewy body dementia (LBD) refers to both dementia with Lewy bodies (DLB) and Parkinson's disease with dementia (PDD). Sleep disturbances are common in LBD, and can include poor sleep quality, excessive daytime sleepiness (EDS), and rapid eye movement behaviour disorder (RBD). Despite the high clinical prevalence of sleep disturbances in LBD, they are under‐studied relative to other dementias. The aim of the present systematic review was to examine the nature of sleep disturbances in LBD, summarise the effect of treatment studies upon sleep, and highlight specific and necessary directions for future research. METHODS: Published studies in English were located by searching PubMED and PSYCArticles databases (until 10 June 2022). The search protocol was pre‐registered in PROSPERO (CRD42021293490) and performed in accordance with PRISMA guidelines. RESULTS: Following full‐text review, a final total of 70 articles were included. These included 20 studies focussing on subjective sleep, 14 on RBD, 8 on EDS, 7 on objective sleep, and 1 on circadian rhythms. The majority of the 18 treatment studies used pharmacological interventions (n = 12), had an open‐label design (n = 8), and were of low‐to‐moderate quality. Most studies (n = 55) included only patients with DLB. Due to the heterogeneity of the studies, we reported a narrative synthesis without meta‐analysis. CONCLUSIONS: At least one form of sleep disturbance may be present in as many as 90% of people with LBD. Subjectively poor sleep quality, excessive daytime sleepiness, and RBD are more common and severe in LBD relative to other dementias.