Comment on “Sleep disturbances and later cognitive status: a multi-centre study”

Alzheimer’s disease (AD) is the main cause of dementia, and age is the best-known risk factor leading to an increase in the prevalence of the disease with ageing populations worldwide (1). Aging is a complex process leading to chronic inflammation and deterioration of the immune function (2), which results in a worsening of the quality of sleep and in an increase in the prevalence of sleep disorders (3). Normal ageing is also characterized by decreased capability to initiate and maintain sleep, which is associated with a decrease in the proportion of slow wave sleep and rapid eye movement (REM) sleep. Sleep patterns are rather heterogeneous, probably due to changes in circadian and homeostatic processes (4).