Excessive daytime sleepiness is independently associated with dehydration among older adults

Excessive daytime sleepiness (EDS) is common in older adults and may contribute to reduced oral intake, potentially increasing the risk of dehydration, which has been linked to adverse health outcomes. We aimed to investigate whether EDS is associated with elevated plasma osmolarity (Posm) in a geriatric population.

In this cross-sectional study, 1,335 adults aged ≥ 65 years attending a geriatric outpatient clinic were assessed. Participants were classified as having EDS (Epworth Sleepiness Scale ≥ 11) or non-EDS. Plasma osmolarity was estimated using a validated formula, with thresholds of > 295 mmol/L for dehydration and > 300 mmol/L for overt dehydration. Clinical, laboratory, and demographic data were collected. Associations between EDS and dehydration were analyzed using univariate and multivariate logistic regression, adjusting for age, sex, comorbidities, and medication use.

EDS was present in 24% of participants. Plasma osmolarity exceeded 295 mmol/L in 56% and 300 mmol/L in 23% of participants. Patients with EDS were older and had higher prevalence of chronic kidney disease, dementia, and polypharmacy. In multivariate analysis, independent predictors of Posm > 300 mmol/L included diabetes mellitus (OR 4.41), chronic kidney disease (OR 5.32), serum sodium (OR 1.76), and EDS (OR 1.51, p = 0.027). EDS was not independently associated with Posm > 295 mmol/L.

In older adults, EDS is independently associated with overt dehydration. Routine assessment of daytime sleepiness may serve as a simple, non-invasive marker to identify individuals potentially at risk, enabling timely hydration interventions and potentially improving health outcomes in aging populations.