Impact of physical fitness and daily energy expenditure on sleep efficiency in young and older humans.

Background: Physical activity is known to influence sleep efficiency. Relatively little is known about the relationship between physical activity and sleep efficiency in young and older humans and the impact of exercise training on sleep efficiency in healthy older individuals.

Objectives: To determine the relationship between physical fitness and daily energy expenditure with sleep efficiency in young and older subjects, and assess the effect of 12-month exercise training on sleep efficiency in healthy older participants.