By Alan Mozes
THURSDAY, Sept. 7, 2017 (HealthDay News) -- Lots of middle-aged American women are fretfully counting sheep each night, new research shows.
The study, from the U.S. Centers for Disease Control and Prevention, found that close to 20 percent of all women aged 40 to 59 said they had trouble falling asleep on four or more nights in the prior week.
Sleep troubles were even more likely if the woman was in the years where she's transitioning into menopause ("perimenopause"). Among these women, more than half (56 percent) said they typically got less than the seven hours of sleep per night that experts deem restful and healthy.
Even after menopause, sleep woes lingered: nearly 36 percent of postmenopausal women aged 40 to 59 said they had trouble staying asleep through the night.
None of this should surprise any woman who's gone through menopause, said one expert who reviewed the study.
Sleeplessness in this period is "going to be about hot flashes, which really start taking place during perimenopause," said Dr. Rajkumar Dasgupta. He is an assistant professor of clinical medicine with the Keck School of Medicine at the University of Southern California, Los Angeles.
"During this time, women can see their body temperature skyrocket, and they can experience night sweats, which means they're experiencing multiple arousals while trying to sleep," he explained.
"There's also the onset of mood changes, the most important of which is depression, which is very strongly associated with insomnia," Dasgupta added. "It's also a time of change -- empty-nest starts happening as kids leave the house, and sometimes there's a mid-life crisis, for both men and women."
The new CDC study analyzed data collected by the 2015 National Health Interview Survey (NHIS), which polled nonpregnant women between the ages of 40 and 59.
The stage of menopause a woman was in seemed to play a big role in whether or not she got good shut-eye. For example, while 56 percent of perimenopausal women failed to get a healthy seven hours of sleep per night, that number dropped to about one-third for premenopausal women, and a little over 40 percent for postmenopausal women.
In terms of sleep quality, however, it was postmenopausal women who were at the biggest disadvantage, the findings showed.
Study lead author Anjel Vahratian explained that "the survey looked at key aspects of sleep quality, such as being able to fall asleep, stay asleep, and feeling well-rested when you wake up in the morning." She helps direct data analysis at the CDC's National Center for Health Statistics (NCHS) in Hyattsville, Md.
According to Vahratian, the data "found that postmenopausal women were the most likely to report having more trouble with all of those issues, four or more times over the past week."
The survey revealed that only about 17 percent of premenopausal women had trouble falling asleep, compared with almost 25 percent among women transitioning into menopause, and more than 27 percent among postmenopausal women.
Similarly, a little under a quarter of premenopausal women said they had trouble staying asleep, compared with almost 31 percent of perimenopausal women, and nearly 36 percent of post-menopausal women, according to the report.
Vahratian said the survey didn't try to determine what might be driving menopause-related differences in sleep.
But Dasgupta noted that, on top of various menopause-linked symptoms, changes in estrogen levels, as well as health issues that come with age, might also play a role.
"Estrogen helps out with muscle tone in the upper airways, and the loss of that contributes to obstructive sleep apnea risk," he pointed out. "Insomnia risk also goes up as we age, along with restless leg syndrome, which interferes with falling asleep. Also as we age, heart failure, lung disease and psychiatric disease risk goes up, and medications to treat these can boost insomnia and the need to go to the bathroom at night."
So what's the advice to America's bleary-eyed women?
"Number one, don't smoke," said Dasgupta. "And for women experiencing hot flashes, wear loose clothes and monitor the room temperature for comfort. Also try and establish good sleep 'hygiene' -- meaning having a defined bedtime and wake time. And, of course, always reach out to your doctor for help."
The new study was published Sept. 7 as an NCHS Data Brief.