Getting too little -- or too much -- sleep may be bad for the heart

Clocking seven or eight hours of shut eye a night seems to be sweet spot for heart health

March 18, 2020

Science Daily/American College of Cardiology

Whether you like to burn the midnight oil to check emails or binge watch your favorite series, toss and turn or sleep until mid-morning, it seems the amount of sleep you get matters when it comes to your future vascular and heart health. Compared with people who slept for longer or shorter periods of time, those who reported sleeping seven or eight hours a night had significantly less evidence of stiffness in their arteries, indicating a lower chance of developing heart disease or suffering a stroke, according to research presented at the American College of Cardiology's Annual Scientific Session Together with World Congress of Cardiology (ACC.20/WCC).

Even after accounting for other known risk factors for heart disease or stroke, people who slept less than six hours or more than eight hours a night had significantly greater odds of having plaque buildup in the walls of their carotid arteries -- a 54% and 39% increase, respectively -- compared with those who got seven or eight hours of shut eye. The study adds to mounting evidence that sleep patterns, similar to diet and exercise, may play a defining role in someone's cardiovascular risk.

"The message, based on our findings, is 'sleep well, but not too well.' Getting too little sleep appears bad for your health but too much seems to be harmful as well," said Evangelos Oikonomou, MD, consultant cardiologist and the study's lead author. "Unlike other heart disease risk factors such as age or genetics, sleep habits can be adjusted, and even after taking into consideration the impact of established risk factors for atherosclerosis and cardiovascular diseases -- for example age, gender, obesity, smoking, hypertension, diabetes, high blood pressure and even a history of coronary artery disease -- both short and long sleeping duration may act as additional risk factors."

For this analysis, researchers assessed sleep patterns in 1,752 people living in the Corinthia region of Greece using a standard questionnaire that was fielded by a trained cardiologist, primary care provider or nurse. Participants were then divided into one of four groups based on self-reported sleep duration: normal (seven to eight hours a night), short sleep duration (six to seven hours a night), very short sleep duration (less than six hours a night) or long sleep duration (greater than eight hours a night). Participants represented a broad spectrum of the general public, including healthy people as well as those with cardiovascular risk factors and established heart disease, and most were from rural areas with less than 1,000-2,000 inhabitants. They ranged in age from 40 to 98 years, with a mean age of 64 years old.

At the time of the study, each participant also underwent ultrasound imaging to measure the thickness of the inner part of the arterial wall. Thickening of the arterial walls reflects plaque buildup and is associated with an increased risk of stroke and other cardiovascular events. Intima media thickness of >1.5 mm or protrusion >50% compared to nearby segments of the artery wall was defined as atherosclerotic plaque.

Researchers uncovered a U-shaped pattern between sleep duration and early indicators of atherosclerosis, which underscores the need for a balanced sleep pattern, Oikonomou said. Intima media thickness and plaque build-up in the artery walls was greater in both the shorter and longer sleep duration groups as compared to normal sleep duration.

"We don't fully understand the relationship between sleep and cardiovascular health. It could be that sympathetic nervous system withdrawal or a slowing [of this system] that occurs during sleep may act as a recovery phase for [usual] vascular and cardiac strain," Oikonomou said. "Moreover, short sleep duration may be associated with increased cardiovascular risk factors -- for example, unhealthy diet, stress, being overweight or greater alcohol consumption -- whereas longer sleep duration may be associated with a less active lifestyle pattern and lower physical activity."

Researchers said that adopting a balanced sleep pattern of six to eight hours nightly may be just what the doctor ordered.

"It seems that this amount of sleep may act as an additive cardioprotective factor among people living in modern western societies, and there can be other health benefits to getting sufficient and quality sleep," Oikonomou added.

The amount of sleep someone needs depends on several factors, especially one's age. In the U.S., most guidelines recommend that adults sleep between seven and nine hours each night. Yet, one out of every three American adults do not get enough sleep, according to the Centers for Disease Control and Prevention. Poor sleep has also been linked to a higher risk of obesity, diabetes, high blood pressure, heart disease, poor mental health and even dying early.

This study is limited in that it relies on self-reported sleep patterns and is cross sectional in nature, so the relationship between sleep patterns and atherosclerotic activity is based on a single point in time. Further research is needed, especially to look at whether too much sleep is harmful, which hasn't been studied as well as getting too little.

https://www.sciencedaily.com/releases/2020/03/200318104451.htm

Can good sleep patterns offset genetic susceptibility to heart disease and stroke?

December 18, 2019

Science Daily/Tulane University

Getting a good night's sleep could be beneficial for long-term health. A pioneering new study led by Dr. Lu Qi, director of the Tulane University Obesity Research Center, found that even if people had a high genetic risk of heart disease or stroke, healthy sleep patterns could help offset that risk. The study is published in the European Heart Journal.

The researchers looked at genetic variations known as SNPs (single nucleotide polymorphisms) that were already known to be linked to the development of heart disease and stroke. They analysed the SNPs from blood samples taken from more than 385,000 healthy participants in the UK Biobank project and used them to create a genetic risk score to determine whether the participants were at high, intermediate or low risk of cardiovascular problems.

The researchers followed the participants for an average of 8.5 years, during which time there were 7,280 cases of heart disease or stroke.

"We found that compared to those with an unhealthy sleep pattern, participants with good sleeping habits had a 35% reduced risk of cardiovascular disease and a 34% reduced risk of both heart disease and stroke," Qi says. Researchers say those with the healthiest sleep patterns slept 7 to 8 hours a night, without insomnia, snoring or daytime drowsiness.

When the researchers looked at the combined effect of sleep habits and genetic susceptibility on cardiovascular disease, they found that participants with both a high genetic risk and a poor sleep pattern had a more than 2.5-fold greater risk of heart disease and a 1.5-fold greater risk of stroke compared to those with a low genetic risk and a healthy sleep pattern. This meant that there were 11 more cases of heart disease and five more cases of stroke per 1000 people a year among poor sleepers with a high genetic risk compared to good sleepers with a low genetic risk. However, a healthy sleep pattern compensated slightly for a high genetic risk, with just over a two-fold increased risk for these people.

A person with a high genetic risk but a healthy sleep pattern had a 2.1-fold greater risk of heart disease and a 1.3-fold greater risk of stroke compared to someone with a low genetic risk and a good sleep pattern. While someone with a low genetic risk, but an unhealthy sleep pattern had 1.7-fold greater risk of heart disease and a 1.6-fold greater risk of stroke.

"As with other findings from observational studies, our results indicate an association, not a causal relation," Qi says. "However, these findings may motivate other investigations and, at least, suggest that it is essential to consider overall sleep behaviors when considering a person's risk of heart disease or stroke."

https://www.sciencedaily.com/releases/2019/12/191218153412.htm