0856 Examining the First Night Effect Among Older Adults with Sleep Disturbances, Cognitive Impairment, and Depression

Abstract Introduction Using electroencephalography-headband (HB) recordings over multiple nights, we examined the first night effect (FNE) among older adults with sleep disturbances undergoing polysomnography (PSG). Methods Ninety-five older adults reporting insomnia and/or daytime sleepiness ≥once/week wore a HB (Beacon Biosignals) for up to seven nights and completed one night of at-home PSG (Nox Medical). Participants also completed questionnaires, including assessments of cognition (Montreal Cognitive Assessment [MoCA]) and depression (Patient Health Questionnaire-8 [PHQ-8]). We compared total sleep time (TST) and wake after sleep onset (WASO) from single-night polysomnography to averages from multi-night HB measures in all participants and among persons with abnormal MoCA scores or with depression. Paired t-tests in the full sample and within subgroups defined by cognitive impairment and depression were used to compare single-night PSG and multi-night HB measures of TST and WASO. Results The average age was 71.8 (SD 7.9) years, 47 (49.5%) were male, 54 (56.8%) were non-Hispanic White, 30 (31.6%) had abnormal MoCA scores, and 18 (18.9%) had depression. For all comparisons, there was no significant difference in measures of TST from single-night PSG vs. multi-night HB measures. WASO in the overall sample was significantly different (102 minutes on PSG vs. 73 minutes on multi-night HB; mean difference of 29 minutes [p< 0.001]). Among persons with abnormal MoCAs, PSG and multi-night HB WASO measures were 116 and 79 minutes, respectively (p=0.005). In those with depression, single-night PSG and multi-night HB WASO measures were 118 and 73 minutes, respectively (p=0.001). Conclusion Among older adults with sleep disturbances, first-night effects were not evident for total sleep time but wake after sleep onset was consistently lower on multi-night home EEG compared with single-night PSG, including among individuals with cognitive impairment or depression. These findings highlight that reliance on a single-night PSG may overestimate WASO in groups where sleep is more fragmented, potentially obscuring true sleep patterns. Multi-night home EEG offers a more representative assessment of nocturnal wakefulness and may improve diagnostic accuracy and treatment planning in patients with cognitive impairment or depression, for whom precise measurement of sleep is particularly important. Support (if any)