Dementia is a major cause of disability worldwide. About 25%-40% of patients with mild to moderate dementia are affected by sleep-awake cycle disturbances, including increased daytime sleepiness and insomnia. However, little is known about the specific impact of excessive daytime sleepiness on the cognitive decline of dementia patients.

To evaluate the impact of daytime sleepiness on the cognitive decline of dementia patients. Additionally, longitudinal associations with functional impairment and neuropsychiatric symptoms will be explored.

A longitudinal study will be conducted in a psychogeriatric consultation. Patients will be consecutively invited according to predefined eligibility criteria. Those aged ≥65 years, with dementia diagnosis or Mini-Mental State Examination (MMSE) <24, and with a knowledgeable caregiver, will be included. The exclusion criteria are: a caregiver <18 years, terminally ill, incapable to communicate or with a known diagnosis of insomnia, sleep related respiratory disorders, central hyperinsomnia, restless legs syndrome or sleep paralysis. Participants will undergo an assessment with a comprehensive protocol including: Montreal Cognitive Assessment (MoCA), Barthel and Lawton Index, Epworth Sleepiness Scale (ESS), Neuropsychiatric Inventory (NPI) and Global Deterioration Scale (GDS). Participants will be re-assessed 6 months after the initial evaluation. The Health Ethics Committee of Hospital Universitário de São João granted the study authorization (nº 260/2020).

Findings will be disseminated via publication in peer-reviewed journals and presentations at national and international scientific conferences.

This study will address key questions on the relation of daytime sleepiness and dementia outcomes, in order to undertake corrective and preventive non-pharmacological and pharmacological approaches.