A new study shows that worse sleep quality predicts lower physical activity in people with post-traumatic stress disorder (PTSD).

Results show that PTSD was independently associated with worse sleep quality at baseline, and participants with current PTSD at baseline had lower physical activity one year later. Further analysis found that sleep quality completely mediated the relationship between baseline PTSD status and physical activity at the one-year follow-up, providing preliminary evidence that the association of reduced sleep quality with reduced physical activity could comprise a behavioral link to negative health outcomes such as obesity.

“We found that sleep quality was more strongly associated with physical activity one year later than was having a diagnosis of PTSD,” said lead author Lisa Talbot, postdoctoral fellow at the San Francisco VA Medical Center and the University of California, San Francisco. “The longitudinal aspect of this study suggests that sleep may influence physical activity.”

Study results are published in the July 15 issue of the Journal of Clinical Sleep Medicine, which is published by the American Academy of Sleep Medicine.