Happily married women report less insomnia.

BALTIMORE--Women who are happily married in midlife report fewer sleep problems than unhappily married or unmarried women, based on data from nearly 3,000 women.

Previous studies have shown that married people, especially women, consistently report less insomnia, compared with their single or divorced counterparts, said Wendy M. Troxel, Ph.D., a psychologist in the department of psychiatry at the University of Pittsburgh. But her study aimed to take a "more nuanced approach to the subject of marriage and insomnia risk by asking whether unhappily or unmarried women are at greater risk for having insomnia symptoms [when compared with] happily married women," said Dr. Troxel, who presented the results at the annual meeting of the Associated Professional Sleep Societies.

The data came from the Study of Women's Health Across the Nation (SWAN), an ongoing longitudinal study being conducted at seven sites in the United States. The goal of SWAN is to characterize the biological and psychosocial changes that occur during perimenopause. The multiethnic study population included women aged 42-52 years at baseline who were not pregnant or breast-feeding and who had an intact uterus.

In this study, Dr. Troxel and her colleagues used participants' self-reports to evaluate 1,938 married women and 997 unmarried women. Women who reported night shift work were excluded.

Overall, most of the married women (83%) were categorized as "happily married" in their current marriages, based on single-item scores in the 4-7 range on the 7-point Likert scale. Choices on this scale ranged from 1 ("extremely unhappy") to 7 ("perfect"). The remaining 17% of married women had scores in the 1-3 range, which characterized them as "unhappily married."

Among the unmarried women, 40% were single, 54% were divorced or separated, and 6% were widowed. Participants met the criteria for insomnia if they reported one or more insomnia symptoms three or more times per week. "Roughly a third of our group had any insomnia symptoms three or more times a week, which is consistent with the prevalence of insomnia in the epidemiologic literature," Dr. Troxel said.

Overall, 45% of the unhappily married women and 40% of the unmarried women met the insomnia criteria, compared with 30% of the happily married women. The difference between the happily married women and both the unmarried and unhappily married women was significant.

When the researchers analyzed the findings by ethnicity, the effect of happy marriage on better sleep remained significant among subsets of white, black, and Hispanic women, but not among Chinese or Japanese women. Japanese women reported the largest percentage of happy marriage (70%), and Chinese women reported the largest percentage of unhappy marriage (15%). Black women reported the largest percentage of being unmarried (52%).

The researchers also examined whether marital happiness was a proxy for other psychosocial and demographic traits that affect insomnia risk. But after adjustment for multiple factors, including age, education, ethnicity, presence of children, employment, use of medication, perceived health status, and "pretty much anything else we wanted to throw into the model," the effects remained the same, Dr. Troxel said.

The unhappily married and unmarried women were significantly more likely to report three or more insomnia symptoms, compared with the happily married women. But no significant differences were found in the number of unhappily married vs. unmarried women who reported three or more symptoms, which suggests that it is not marriage itself that is beneficial for sleep, Dr. Troxel observed. "Marriage may be good for women's sleep, but only if it is a happy one," she said.

The study was limited by its focus on older women; the results might not be generalizable to younger women. Also, no data were available on sleep problems before marriage. "We need to do studies to examine the bidirectional effect of marriage on sleep, and we need objective measures," Dr. Troxel said.

Dr. Troxel said her study was supported in part by a grant from the National Institutes of Health.

BY HEIDI SPLETE

Senior Writer