Cognitive Functioning in the Community Elderly: The Role of Sleep and Caffeine

Deteriorations in cognitive functioning and sleep are the inevitable parts of the ageing process, and they are two very common complaints among the elderly population. Given their high relevance and great impact on daily functioning, many studies have attempted to address the associations of sleep problems and cognitive functioning with ageing, but the direction of associations remained unclear. Several recent studies suggested that caffeine might have a beneficial effect on age-related decline in cognitive functioning. Nonetheless, the dose-dependent effect of caffeine intake on specific domains of cognitive functioning, and the potential cost of compromised nocturnal sleep at high dose of caffeine remained to be investigated. In view of the lack of study on identifying the correlation and interaction between sleep, cognitive functioning, caffeine consumption habit, and age, two studies were conducted to clarify these relationships in the elderly population.