Sleep-wake cycle disturbances in elderly acute general medical inpatients: longitudinal relationship to delirium and dementia.

Introduction: Sleep disturbances in elderly medical inpatients are common, but their relationship to delirium and dementia has not been studied. Methods: Sleep and delirium status were assessed daily for a week in 145 consecutive newly admitted elderly acute general hospital patients using the Delirium Rating Scale-Revised-98 (DRS-R98), Diagnostic and Statistical Manual 5, and Richards-Campbell Sleep Quality Scale measures. The longitudinal relationship between DRS-R98 and Richards-Campbell Sleep Quality Scale sleep scores and delirium, also with dementia as a covariate, was evaluated using generalized estimating equation logistic regression. Results: The cohort was divided into delirium only, dementia only, comorbid delirium-dementia, and no-delirium/no-dementia subgroups. Mean age of total group was 80 6 6.3, 48% were female, and 31 (21%) had dementia, 29 had delirium at admission (20%), and 27 (18.5%) experienced incident delirium.Mild sleep disturbance (DRS-R98 sleep itemscore 1) occurred for at least 1 day in all groups, whereasmoderate sleep disturbance (score 2) occurred in significantlymore of the prevalent deliriumonly (81%; n517) cases than incident delirium-only (46%; n513) cases (P,.001). Therewere more cases with DRS-R98 sleep item scores 2 (P ,.001) in the delirium-only group compared with the other subgroups. Severity of sleep-wake cycle disturbance over time was significantly associated with Diagnostic and Statistical Manual 5 delirium status but not with age, sex, or dementia (P ,.001). Conclusions: Observer-rated more severe sleep-wake cycle disturbances are highly associated with delirium irrespective of dementia status, consistent with being a core feature of delirium. Monitoring for altered sleep-wake cycle patterns may be a simple way to improve delirium detection.