Sleep Disturbances Across the Clinical Continuum of Alzheimer's Disease: Associations with Disease Duration and Care Environment—A Cross-Sectional Study

Background Sleep disturbances are among the most common non-cognitive manifestations of Alzheimer's disease (AD) and contribute to functional decline, reduced quality of life, and caregiver burden. Although sleep impairment has been widely investigated in AD, the influence of care setting on sleep disturbances and their relationship with disease duration remains poorly understood. This study evaluated the prevalence and characteristics of sleep disturbances in patients with AD and examined their associations with disease duration, daytime napping, and care setting. Methods This cross-sectional study included 70 patients with clinically diagnosed AD recruited from nursing homes (n = 51) and community-based support services (n = 19). Sleep disturbances were assessed using a structured study-specific questionnaire supported by caregiver reports, the Athens Insomnia Scale (AIS), and the Epworth Sleepiness Scale (ESS). Cognitive and functional status was assessed using standardised clinical instruments. Associations between sleep disturbances and clinical variables were analysed using non-parametric statistical methods. Results Sleep disturbances were highly prevalent. The most common symptoms were excessive daytime sleepiness (90.0%), nocturnal awakenings (84.3%), difficulty initiating sleep (74.3%), and snoring (62.9%). Sleep-related symptoms preceding the clinical diagnosis of AD were reported in 47 participants (67.1%). Greater sleep disturbance burden was associated with longer disease duration (Spearman's ρ = 0.26, p = 0.030) and daytime napping (p = 0.0047). Nursing home residents had a greater sleep disturbance burden than community-dwelling participants (median 8 [IQR 6–9] vs 6 [5–7], p = 0.006) and also had higher AIS (10 [9–12] vs 6 [3–10], p = 0.0065) and ESS scores (9 [8–12] vs 7 [5–8], p = 0.0013). Conclusions Sleep disturbances are highly prevalent throughout the course of AD and may precede its clinical diagnosis. Greater sleep disturbance burden was associated with longer disease duration and was higher among nursing home residents than community-dwelling participants. These findings support systematic assessment of sleep disturbances as part of comprehensive dementia care across different care settings. Longitudinal studies incorporating objective sleep measures are needed to clarify the temporal relationships between sleep disturbances, disease progression, and care environment.