Hot Flashes, Sleep Disturbances Studied in Perimenopausal Women with Breast Cancer

Co-occurring hot flashes and sleep disturbances are a major public health concern for perimenopausal women. Experts estimate that 40 percent of women in midlife have mild sleep disturbances related to hot flashes, while another 30 percent report moderate disturbance and 6 percent have sleep disturbances so relentless that they qualify as severe insomnia. Subsequent fatigue interferes with activities of daily living, decreases productivity, and has significant yet understandable effects on mood.

Studies examining hot flashes and sleep are notoriously difficult to design, as both sleep and hot flashes are poorly understood. What researchers do know is that hot flashes are vasomotor symptoms triggered or exacerbated by plummeting estrogen levels. The symptoms may occur naturally or be chemically induced by abrupt cessation of chemotherapy and hormone therapy such as tamoxifen. That’s why breast cancer patients who take adjuvant drugs to reduce their chances of recurrence report hot flashes and insomnia more often than normal controls. For those patients, clinicians have limited treatment management options.

Researchers from the Laval University Cancer Research Center in Quebec, Canada, set out to assess the relationship between various characteristics of nocturnal hot flashes and sleep disturbances in women who are treated for non-metastatic breast cancer. They hypothesized that more frequent and severe hot flashes would be significantly associated with alterations in the patients’ sleep macrostructure. To test their hypothesis, the researchers measured REM sleep latency, sleep efficiency, EEG measures of arousability, and frequency and mean duration of nocturnal awakenings in 56 women with a mean age of 52 years old.

At breast cancer diagnosis, 34 participants were perimenopausal. However, after chemotherapy and during hormone therapy with tamoxifen, anastrazole, exemestane or letrazole, all participants were either perimenopausal or postmenopausal.

Women whose nocturnal hot flashes reached their peak more slowly and lasted longer had greater total wake time, poorer sleep efficiency, higher frequency of nocturnal awakenings, and shorter duration of REM sleep during the first third of the night. Additionally, women who experienced higher numbers of hot flashes were significantly more likely to have EEG changes.

The researchers also found that significantly more sleep disturbances occurred during hot flash onset and plateau compared to the period before the hot flash started. Further, sleep disturbances were noteworthy, as women reported and the researchers confirmed lighter sleep, longer periods of sleeplessness, and 13.3 awakenings lasting more than 1 minute per night on average.

Despite those findings, the researchers neither offered clinical advice nor proposed a physiologic mechanism to explain the associations.

Though estrogen with or without progestin remains the only treatment approved by the US Food and Drug Administration (FDA) for menopausal hot flashes, use of the hormone therapy markedly declined after the release of the Women’s Health Initiative Estrogen Plus Progestin Trial results. For women who must avoid estrogen because they have breast cancer or are at risk of developing breast cancer, researchers suggest that selective serotonin reuptake inhibitors with zolpidem taken early in the day can address both hot flashes and sleep disturbances.