Book Description

With life expectancy on the rise, the proportion of people aged 60 or older is projected to account for more than one-fifth of the global population by 2050. Sleep quality is one of the most common health concerns that increases with age. Changes in sleep patterns associated with old age include disturbed sleep onset, an increase in sleep fragmentation, more frequent daytime dysfunction, and less slow-wave sleep than younger adults. Sleep is a complex physiological process critical to our health and survival; the many functions of sleep range from cerebral metabolic waste clearance and energy conservation to supporting cognitive performance and psychological well-being. Insufficient sleep has been linked to an increased risk of developing several chronic conditions, including type 2 diabetes, cardiovascular disease, immunodeficiency, chronic pain, depression, and neurodegenerative diseases such as dementia due to Alzheimer’s disease. What remains unclear is how variations in sleep quality are related to cognitive performance and how this relationship changes with age, with several decades of research on the subject having produced mixed results. Despite this, much recent evidence indicates a strong relationship between disturbed sleep and accelerated cognitive decline in older adults. For example, several studies have found that a loss in sleep quality precedes the emergence of cognitive deficits and that sleep disturbances may therefore constitute an early marker of cognitive decline. Sleep disturbances also become more extensive with the progression of neurodegenerative diseases, which raises questions about the possibility of a bidirectional relationship.