Sleep in Healthy and Pathological Aging

Human sleep physiology is strongly affected by age. Indeed, healthy aging is characterized by relevant changes in sleep habits, sleep macrostructure, and electroencephalographic (EEG) sleep features [1]. Moreover, the diurnal modulation of sleepiness and vulnerability to sleep loss change with age [1], and the prevalence of several sleep disorders shows an age-related increase [2]. Sleep changes in older individuals may be influenced by several factors, such as an increase in different pathological conditions (and the parallel increase in medication use, with a high frequency of polypharmacotherapy) and age-related environmental and psychosocial changes [2]. However, the presence of sleep and sleep-related alterations in older individuals can have relevant functional consequences in terms of reduced physical and mental health and quality of life [3], as well as direct effects on cognitive functioning [1]. It is worth noting that several age-related pathological conditions are characterized by significant sleep alterations. In particular, sleep/wake cycle disruption, sleep pattern changes, and increased sleep disorders are typical in neurodegenerative disorders such as Alzheimer’s disease (AD) and Parkinson’s disease (PD) (e.g., [4,5]). Crucially, a growing body of evidence suggests that specific sleep alterations may predict neurodegenerative processes and may play a role in the etiopathogenesis of AD [5]. In this regard, the possible relevance of sleep-based interventions in the pre-clinical stage and during the course of AD pathology has been highlighted [6]. The growing literature underlines the need for a better understanding of the causes, consequences, and functional significance of age-related sleep changes; their relationship with pathological conditions; and their possible role in clinical settings, especially considering that the aging population is progressively growing. Starting from this premise, the present Special Issue aimed to collect articles focused on sleep in healthy and pathological aging using different methodologies. In this editorial, we highlight the main contents of each contribution to this Special Issue in order to encourage the reader to explore them in detail.