WASHINGTON – Women have another reason to get a good night’s sleep. Poor sleep in general and waking up too early in particular can be bad for women’s hearts.

A University of California – San Francisco study shows poor sleep, defined as less than 6 hours a night, significantly boosts unhealthy levels of inflammation in female heart patients.

“Now we have evidence that poor sleep appears to play a bigger role than we had previously thought in driving long-term increases in inflammation levels and may contribute to the negative consequences often associated with poor sleep,” says the study’s lead author Aric Prather.

The negative impact did not extend to men in the study.

More research is needed to explain the gender difference, but doctors think testosterone in men might block the negative effects of poor sleep.

The five-year study included women and men in their 60s all of whom had stable coronary heart disease. The study was published in the Journal of Psychiatric Research

For the purposes of the study “poor sleep” is defined as getting fewer than six hours a night.