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Night sweats and hot flashes affect a restful sleep and brain function

This article featured in the November, 2019 edition of Contemporary OBGYN magazine:

In a group of patients with breast cancer where hormonal replacement therapy (HRT) was not deemed safe, hot flashes and night sweats seemed to affect the quality of sleep and brain function the following day. Unfortunately sleeping more to compensate for the poor sleep quality seemed to worsen the brain function the next day.

These findings need be tested in a population of menopausal women with hot flashes and night sweats but without breast cancer. I have many patients reporting that their HRT helps them with their "brain fog", "memory issues" and mood stability. It would be interesting to see how hormone replacement therapy might improve the quality of sleep and brain function as a result in a large study.

Here is the article:

Menopausal night sweats linked to impaired cognitive function

Bob Kronemyer

November 8, 2019

Menopausal women with frequent night sweats have more sleep, but that may not be a plus for brain function, according to a study presented at The North American Menopause Society (NAMS) Annual Meeting in Chicago in September.

“Paradoxically, women who experience night sweats may be vulnerable to prefrontal cortex deficits like decreased attention and executive function as their total sleep time increases,” said lead author  John Bark, a PhD candidate in behavioral neuroscience at the University of Illinois at Chicago. Bark said roughly 50% of menopausal women experience sleep difficulty and about 80% of menopausal women experience hot flashes and night sweats.


The study is a secondary analysis of a pilot trial using a stellate ganglion blockade (SGB) to treat vasomotor symptoms in women with a history of breast cancer, which was conducted at both the University of Illinois at Chicago and Northwestern University.

“Women with breast cancer are more prone to having hot flashes, and breast cancer induces early menopause,” said Bark, who was part of the pilot trial as well. “The medications that these women take also increase the severity and the frequency of hot flashes.”  

All of the 33 study patients were menopausal, had a history of breast cancer, and had moderate-to-severe hot flashes or night sweats (at least four episodes a day), which were confirmed by wearing ambulatory skin-conductance monitors for a 24-hour period. Sleep was assessed with actigraphy, while cognition was assessed by comprehensive neuropsychological testing.

“In this particular study, we were focused on using the digit span forward, the digit span backward and semantic fluency,” Bark told Contemporary OB/GYN. “These are all attention and executive functioning measures.”


Using linear models, the authors looked at how total sleep time and cognition were impacted by night sweats and daytime hot flashes, and how the sweats and flashing interacted to affect cognition. In women who had both night sweats and hot flashes during the day, there was a significant impact on tests of cognitive function (β = -0.02, P = .01) as well as digit span forward and backward (β = -0.001, P = .003 and β = 0.004 and P = .01, respectively).


The study found that total sleep time was not linked to attention and executive functioning, which is counterintuitive, according to Bark. “Instead, we found the effect of sleep on memory was dependent on the number of night sweats,” he said. “We concluded that women without night sweats had improved cognitive performance with more sleep. In other words, the more sleep they had, the better they performed on attention and executive functioning measures, whereas women with a high number of night sweats had a negative association between sleep and attention and executive functioning, such that more sleep is harmful to cognition.”

The counterintuitive finding might be attributed to night sweats causing a need for even more sleep. “There are also women who sleep more, so if you sleep more you have more night sweats,” Bark said.

Based on study results, sleep is a risk factor for attention and executive functioning difficulties in menopause. “However, a clinician can intervene by treating hot flashes,” Bark said.

Bark and his colleagues hope to replicate results in a larger study of women with moderate-to-severe hot flashes, but without a history of breast cancer.