Disclosures: The authors report no relevant financial disclosures.
August 04, 2020
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Phthalates may contribute to sleep disruption in menopause

Disclosures: The authors report no relevant financial disclosures.
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Phthalate exposure may negatively affect sleep quality for midlife women, according to a study published in Menopause.

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“There are many causes of menopausal symptoms that we are still trying to identify,” Katherine Hatcher, PhD, a postdoctoral researcher in reproduction and neuroendocrinology at Albany Medical College, and Megan Mahoney, PhD, associate professor in neuroscience at University of Illinois at Urbana-Champaign, told Healio. “It may be important to consider a woman’s exposure to environmental chemicals as a potential source contributing to a woman’s menopausal symptoms. This may lead to changes in treatment, such as educating women on how to reduce their exposure to environmental contaminants.”

Katherine Hatcher
Megan Mahoney

Hatcher, Mahoney and colleagues analyzed data from the Midlife Women’s Health Study, which started in 2006. The study included 762 women aged 45 to 54 years (459 premenopausal and 303 perimenopausal) from the Baltimore metropolitan area. At a first clinic visit, participants completed a 26-page demographic survey and answered questions about frequency of sleep disturbances and insomnia on a five-point scale and frequency of restless sleep on a four-point scale. Among the cohort, 419 participants reported they were nonsmokers, 269 indicated they were former smokers and 78 indicated they were current smokers. Participants also submitted blood and urine samples and had height, weight and blood pressure measured; additional samples were taken at visits during the following 3 weeks.

After adjusting for BMI, menopause status, reported nighttime hot flashes, smoking status, and depressive symptom and quality of life scores, lower concentrations of progesterone were associated with increased sleep disturbances (beta = 0.15; 95% CI, 0.27 to 0.043) and insomnia (beta = 0.12; 95% CI, 0.26 to 0.014). Lower concentrations of testosterone also were associated with increased sleep disturbances (beta = 0.31; 95% CI, 0.63 to 0.0072) and insomnia (beta = 0.34; 95% CI, 0.69 to 0.023). Increased insomnia was associated with a lower free testosterone index (beta = 0.05; 95% CI, 0.11 to 0.0014).

Researchers found significant associations among endogenous hormones, sleep disruption and nonsmoking status. Among nonsmokers, lower progesterone levels were associated with more frequent sleep disturbances (beta = 0.12; 95% CI, 0.26 to 0.014) and lower testosterone levels were associated with increased insomnia (beta = 0.4; 95% CI, 0.81 to 0.015). A lower free estradiol index was associated with more sleep disturbances (beta = 0.68; 95% CI, 1.3 to 0.061) and insomnia (beta = 0.77; 95% CI, 1.5 to 0.1), and a lower free testosterone index was associated with increased insomnia (beta = 0.064; 95% CI, 0.13 to 0.0094). A higher estradiol-progesterone ratio was associated with increased sleep disturbances (beta = 1.2; 95% CI, 0.26-2.2), insomnia (beta = 1; 95% CI, 0.061-2) and restless sleep (beta = 0.9; 95% CI, —0.072 to 1.9).

Results also showed significant associations between phthalate exposure and sleep disruption and former-smoker status. Among nonsmokers, higher levels of phthalates from plastics were associated only with more sleep disturbances (beta = 0.91; 95% CI, 0.25-1.6). Among former smokers, lower levels of phthalates from personal care products were associated with increased insomnia (beta = 0.71; 95% CI, 1.4 to 0.09), and lower concentrations of phthalates from plastics were associated with more sleep disturbances (beta = 8; 95% CI, 17 to 0.27) and insomnia (beta = 9.9; 95% CI,  20 to 1.2).

There were no statistically significant associations between any of the hormone measures or phthalates and sleep disruptions for current smokers. The researchers wrote that smoking could influence sleep either through directly altering hormone concentrations or indirectly through additional symptoms.

“Smoking status may be an important confounding factor when one considers the impact of hormones and endocrine-disrupting chemical exposure, particularly in the context of self-reported sleep disruptions and midlife women,” the researchers wrote.

In addition to identifying potential interventions for reducing exposure to environmental chemicals and mitigating their effects on sleep, Hatcher and Mahoney said, future research should examine the relationship between sleep and chemicals other than phthalates.

“We did find that women with the highest concentrations of phthalates had fewer sleep disruptions,” they told Healio. “However, another way to think about these data is to consider that all of the women we studied had relatively low human exposure levels to phthalates, compared to occupational exposure levels, for example. Then, within this group of relatively low exposures, the women with the lowest exposure levels to phthalates also had the highest levels of sleep disturbances. This has implications for the general population of people.

“Finally, what we can say is that there is a relationship between phthalate exposure and sleep quality, and we will need to expand the population to include more women with relatively higher exposure in order to more fully understand this relationship between exposure and sleep,” they said.

For more information:

Katherine Hatcher, PhD, can be reached at hatchek@amc.edu; Twitter: @superchiasmatic.

Megan Mahoney, PhD, can be reached at mmm1@illinois.edu.