There is mounting evidence suggesting that sleep plays a big role in heart health. Indeed, the evidence has become compelling enough for the American Heart Association to update their Life’s Simple 7, the seven most important predictors of heart health, Life’s Essential 8, adding healthy sleep as a critical part of achieving and maintaining heart health.
A new study, presented to this year’s European Society of Cardiology (ESC) Congress, adds to the body of knowledge supporting the connection between healthy sleep and better heart health. According to the results of that study, getting optimal sleep is linked to a 74 percent lower cardiovascular disease or ailment risk.
How Researchers Define Optimal Sleep
Most of the previous studies looking at the potential connections between sleep and cardiovascular disease risk placed their research focus on a single element of sleep, such as the number of hours slept or the potential impact of a sleep disorder, such as sleep apnea.
However, in this recent study, conducted by French National Institute of Health and Medical Research researchers, a different, more broad approach was taken. These researchers decided to look at the impact of not just the amount of sleep, but also the quality of sleep as well as other facets of sleep health and habits.
The researchers used health data from just over 7,200 heart healthy men and women ranging in age from 50 to 75 years old. Participants had physical exams and biological testing, as well as providing medical history and lifestyle information, including sleep health and habits. Regarding sleep, the researchers inquired about how many hours they slept, whether they experienced insomnia, whether or not they fell into an early rising chronotype, if they had sleep apnea and if they experienced daytime sleepiness.
The researchers devised a sleep scoring system based on how they defined optimal sleep: having an early chronotype, more in line with the sun than a late chronotype or a night owl tends to be, getting between seven and eight hours of sleep nightly, not or rarely experiencing insomnia and not having sleep apnea or often experiencing daytime sleepiness. Participants were scored a point for each of those five sleep health measures that were true about their sleep patterns and a zero for those that were untrue or did not meet the optimal standard.
What the Results Revealed
Approximately eight years after that initial collection of data, which was done between 2008 and 2011, the researchers collected follow-up health data on the study participants. Upon reviewing that follow-up data, the researchers found that those with a sleep score of 5 had 74 percent less of a risk of developing cardiovascular problems than those with the lowest sleep score, linking optimal sleep to better heart health.
According to the researchers, each point was linked to a 22 percent decrease in the risk of experiencing cardiovascular health issues. In practical terms, that potentially means that you can gradually lower the risk to your heart health by working to improve each of those sleep quality measures.
Various Theories Could Explain Mechanisms Involved
While researchers have confirmed the link between optimal levels and habits of sleep and heart health, a definitive statement of causation is still out of reach, primarily because the mechanisms involved are still not fully understood. However, there are some interesting theories being offered by a range of researchers and experts in the field, including those not directly involved in this specific study.
Disrupted sleep, for example, can lead to disruption in the timing of hormone production and function. It’s one of the reasons that insufficient and poor-quality sleep is linked to a higher risk of obesity, insulin resistance and type two diabetes. Insulin is a hormone, as is ghrelin, which stimulates the appetite. Levels of ghrelin have been shown to be higher in those with insufficient sleep.
Board-certified cardiologist Dr. Rigved Tadwalkar, not on the team of French researchers, noted that insufficient sleep can impact the sympathetic nervous system, increasing the release of catecholamines, hormones that promote higher heart rate, higher blood pressure and increased vascular resistance. Dr. Saurav Luthra, from the Division of Pulmonary, Critical Care, and Sleep Medicine of the University of Kansas Health System explained that poor sleep can increase the flow of stress hormones, increasing nighttime blood pressure and heart rate.
Poor sleep is also associated with increased inflammation risk. According to the American Heart Association, inflammatory processes are associated with higher risks of cardiovascular diseases. Dr. Luthra also mentioned inflammation as a result of insufficient sleep, as well as disruption of the processes involved in flushing toxins from the brain.
Best Time to Go to Sleep
A 2021 study published in the European Heart Journal found that, in terms of heart health, the best time to go to sleep is between 10:00 p.m. and 11:00 p.m. The study used data collected from 103 712 UK Biobank participants via wrist-worn devices called accelerometers.
According to the data, the window between 10:00 and 11:00 is ideal: Going to bed before 10:00 p.m. or after 11:00 p.m. was associated with a higher risk of cardiovascular disease. Interestingly, the association between bedtime and heart health was stronger in women than it was for men.