Memory problems in older women may contribute to sleep troubles, new research suggests.

Researchers studied nearly 2,500 women with an average age 69. Those who showed signs of mental decline on the tests were nearly twice as likely to have difficulty staying asleep and one-and-a-half times as likely to have problems falling asleep, according to researchers at the University of California. Subjects with cognitive decline also had a higher rate of being awake for more than 90 minutes during their sleep cycle, the study found.

Women studied showed no signs of memory problems at the beginning of the study, but they underwent cognitive tests as well as assessments for sleep problems over the 15-year period of the study. Memory loss may increase the risk of sleep problems, either because they share common underlying changes in the brain or because women with memory problems also may be anxious or depressed. The study was published in the journal Neurology.