A common but significant change associated with aging is a profound disruption to the daily sleep-wake cycle. It has been estimated that as many as 50% of older adults complain about difficulty initiating or maintaining sleep. Poor sleep results in increased risk of significant morbidity and mortality. Moreover, in younger adults, compromised sleep has been shown to have a consistent effect on cognitive function, which may suggest that sleep problems contribute to the cognitive changes that accompany older age. The multifactorial nature of variables affecting sleep in old age cannot be overstated. Changes in sleep have been thought to reflect normal developmental processes, which can be further compromised by sleep disturbances secondary to medical or psychiatric diseases (e.g., chronic pain, dementia, depression), a primary sleep disorder that can itself be age-related (e.g., Sleep Disordered Breathing and Periodic Limb Movements During Sleep), or some combination of any of these factors. Given that changes in sleep quality and quantity in later life have implications for quality of life and level of functioning, it is imperative to distinguish the normal age-related sleep changes from those originating from pathological processes.