Hypertension linked to irregular sleep, 'forever chemicals'
An increased risk of high blood pressure has been linked to irregularities in sleep as well as to higher concentrations of per- and polyfluoroalkyl substances in the blood, according to two new studies.
An Australian study of more than two million nights of sleep and blood pressure data found that irregularities in sleep timing and duration were associated with an increased risk of hypertension. The research abstract was published in an online supplement of the journal Sleep and presented during SLEEP 2022, the annual meeting of the Associated Professional Sleep Societies.
Flinders University researchers analysed data collected over nine months from 12,300 participants who were between 18 and 90 years old, with metrics recorded via an under-mattress sleep device and a portable blood pressure monitor. Logistic regressions controlling for age, sex, body mass index and mean total sleep time were conducted to investigate potential associations between sleep regularity and hypertension, which was found in 2499 participants.
Results show that high sleep duration irregularity was associated with a 9% to 15% increase in hypertension risk. Furthermore, a 38-minute increase in sleep midpoint irregularity was associated with an 11% risk increase, and a 31-minute increase in sleep onset time irregularity was associated with a 29% increased risk of hypertension.
“These new insights into the potential adverse impact of irregular sleep timing and duration on heart health further highlight the importance of ... synchronising the body clock and prioritising enough sleep opportunity for optimal health and wellbeing,” said senior author Professor Danny Eckert, Director of the Flinders Health and Medical Research Institute (FHMRI): Sleep Health.
The researchers noted that prior studies of sleep and heart health have been limited in sample size and restricted to a short period of time. The current study investigated associations between sleep regularity and hypertension in a large, global sample over multiple months.
“This new approach to non-invasive nightly monitoring of sleep duration and timing in people’s homes for an average period of six months each, combined with regular blood pressure monitoring, has shown us just how important having a regular sleep routine and getting enough sleep is for your health, in this case your heart health,” said lead author Dr Hannah Scott, also from FHMRI: Sleep Health.
“These novel data shed new light into the restorative benefits of sleep and raise potential concerns for the substantial proportion of shift workers in our modern 24-hour society.”
US researchers have meanwhile found that middle-aged women with higher blood concentrations of common synthetic chemicals called per- and polyfluoroalkyl substances (PFAS), also called ‘forever chemicals’ as they never degrade in the environment, were at greater risk of developing high blood pressure compared to their peers who had lower levels of these substances. The study was published in the journal Hypertension.
There are thousands of different PFAS that are used in everyday household items, such as certain shampoos, dental floss, cosmetics, non-stick cookware, food packaging, and stain-resistant coatings for carpeting, upholstery and clothing. The chemicals also enter the food system through fish caught in PFAS-contaminated water and dairy products from cows exposed to PFAS through fertilisers on farms, for example.
Nearly all Americans have detectable concentrations of at least one PFAS in their blood, and this can have detrimental health effects even at low levels. Some PFAS have been linked to cardiovascular risk, including endothelial dysfunction (impaired blood vessel function), oxidative stress and elevated cholesterol. However, no previous studies have evaluated whether PFAS levels affect blood pressure control among middle-aged women.
“Women seem to be particularly vulnerable when exposed to these chemicals,” said study lead author Ning Ding, a postdoctoral fellow at the University of Michigan School of Public Health. “Our study is the first to examine the association between forever chemicals and hypertension in middle-aged women.”
Using data from the Study of Women’s Health Across the Nation-Multi-Pollutant Study (SWAN-MPS), a prospective study of over 1000 racially diverse middle-aged women over an 18-year period, researchers examined blood concentrations of specific PFAS and the risk of high blood pressure. The analysis found:
- During 11,722 person-years of follow-up for all study participants, 470 women developed high blood pressure.
- Women with higher concentrations of specific PFAS were more likely to develop high blood pressure: women in the highest one-third concentrations of perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA) and 2-(N-ethyl-perfluorooctane sulfonamido) acetic acid (EtFOSAA, a PFOS precursor) had 42%, 47% and 42% higher risks, respectively, of developing high blood pressure, compared to women in the lowest one-third concentrations of these PFAS.
- Women in the highest one-third concentrations of all seven PFAS examined had a 71% increased risk of developing high blood pressure.
“We examined individual PFAS as well as several PFAS together, and we found that the combined exposure to multiple PFAS had a stronger effect on blood pressure,” said study senior author Sung Kyun Park, an associate professor at Michigan.
“We have known for some time that PFAS disrupt metabolism in the body, yet we didn’t expect the strength of the association we found. We hope that these findings alert clinicians about the importance of PFAS and that they need to understand and recognise PFAS as an important potential risk factor for blood pressure control.”
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