DENVER – Much of the rising prevalence of insomnia among U.S. and Canadian adults may be driven by the sharp reduction in the use of hormone replacement therapy following the 2002 report from the Women’s Health Initiative, Sheila N. Garland, PhD, said at the annual meeting of the Associated Professional Sleep Societies.
“In 2002 the Women’s Health Initiative came out with findings that hormone replacement therapy increased the risk of coronary heart disease, breast cancer, stroke, and pulmonary embolism [JAMA. 2002 Jul 17;288(3):321-33]. A lot of women on hormone replacement therapy up until 2002 stopped using it then. The increase in difficulty sleeping we found between 2002 and 2012 could perhaps represent an untreated menopausal symptom,” according to Dr. Garland, a psychologist at Memorial University of Newfoundland in St. John’s.
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She presented an analysis of data from the Canadian Community Health Survey, a national once-per-decade survey, which included 34,118 adults aged 20-80 years and older in the 2002 version and 23,089 in 2012.
The key finding from the standpoint of sleep medicine, the prevalence of self-reported trouble sleeping, increased from 15.6% in 2002 to 17.1% in 2012. And this increase was concentrated in 40- to 59-year-old women, where the prevalence of insomnia or poor sleep rose from 19% to 24.3%, the highest of any age group. Rates remained flat over time in men and women aged 20-39 years and 60-80 years and older as well as in 40- to 59-year-old men.
The sleep-related question put to survey participants in face-to-face or telephone interviews was this: “How often do you have trouble going to sleep or staying asleep?” If they answered “most of the time” or “all of the time” they were classified as having poor sleep.
When Dr. Garland saw the survey results she immediately asked herself, “What is happening with Canadian women?” She came up with two theories. They are not mutually exclusive. One hinges on the dramatic drop off in the use of hormone replacement therapy in response to the Women’s Health Initiative report. The other theory is that the increasing prevalence of insomnia in middle-aged women is a manifestation of stress among the growing population of what has been called “the sandwich generation,” people who care for their aging parents while also supporting their own children. Those responsibilities most often fall upon the mother.
She noted that a similar rise in the prevalence of insomnia or trouble sleeping is occurring south of the border – in the United States – as documented in a Centers for Disease Control and Prevention analysis. The CDC investigators examined data on 30,970 adult participants in the 2002 National Health Interview Survey, 23,344 in the 2007 survey, and 34,509 in the 2012 survey. The prevalence of insomnia or trouble sleeping increased from 17.5% in 2002 to 19.2% in 2012. That absolute 1.7% increase pairs well with the 1.5% rise over the same time frame in the Canadian survey. The prevalence was higher in U.S. women than men in all three survey years (Sleep Med. 2015 Mar;16[3]:372-8).
Dr. Garland said the Canadian national survey contains data on self-perceived stress levels. She plans to analyze those results to learn if being a member of the sandwich generation is a significant contributor to poor sleep.
Regardless of the underlying mechanism, she continued, it’s clear from these large national surveys that middle-aged women are particularly vulnerable to poor sleep.
“Increased recognition is necessary. Prevention and intervention programs may be warranted, given the individual and societal consequences of poor sleep, including increased psychiatric and medical disorders, work absenteeism, and health care costs,” she said.
One audience member rose to congratulate Dr. Garland on her detective work. He commented that her notion that the rise in insomnia can be traced to fallout from the 2002 Women’s Health Initiative is consistent with his own clinical experience.
“The most common way women over age 40 present to our sleep center with insomnia is because they’re menopausal and not on hormone replacement therapy,” he said.
The Canadian Community Health Survey is sponsored by Statistics Canada. Dr. Garland reported having no financial conflicts of interest.