Lack of sleep is associated with poorer physical function in older women during daytime hours, a University of Pittsburgh study found.

Suzanne E. Goldman, of the University of Pittsburgh, studied 2,889 women who participated in the 2002-2004 examination of the Study of Osteoporotic Fractures.

The subjects wore actigraphs, which measured sleep variables including total sleep time and hours awake after sleep onset during the night and daytime napping behavior. Neuromuscular performance measurements included gait speed, chair stands and grip strength, while functional limitations were assessed as self-reported difficulty with one or more of six instrumental activities of daily living.

The study, published in the journal Sleep, found women who slept less than six hours per night walked 3.5 percent slower than those who slept 6 to 6.8 hours.

"The results suggest that those women with more disrupted sleep as characterized by shorter sleep duration and longer wake time during the night, and those with greater daytime sleepiness as characterized by napping behavior, were at greater risk for poorer neuromuscular performance and poorer daytime function," Goldman said.