Most of us know that not getting enough sleep is bad for us.
Yet many people believe their busy lives require that they skimp on sleep. As Elon Musk recently posted on Twitter at 2:30 a.m. (after being criticized by Ariana Huffington for working so many hours and sleeping so few), "I just got home from the factory. You think this is an option. It is not."
But the lengthy list of negative ways that lack of sleep affects your body and brain continues to grow. According to several new studies presented Sunday at a meeting of the European Study of Cardiology, getting too little — or too much — sleep is associated with significant increased risk for cardiovascular problems including hardened arteries, heart attacks, strokes, heart failure, and more.
"We spend one-third of our lives sleeping yet we know little about the impact of this biological need on the cardiovascular system," Dr. Epameinondas Fountas, one of the authors of a meta-analysis about the best amount of sleep for heart health, said in a news release.
Fountas' team looked at 11 studies with more than 1 million participants, and their findings shed more light on the impacts of sleep deprivation. The results give us even more reasons to try to fit enough sleep into our lives.
What happens if you don't get enough sleep
Although individual needs may vary, sleep researchers generally say people should get seven to nine hours of shut-eye per night. That's considered the amount that's optimal for good cognitive performance, safety, and brain health, and for lower risk of cancer and death.
When it comes to cardiac disease, the authors of the meta-analysis found that the sweet spot for lowest risk was six to eight hours of sleep per night. Averaging less than that was associated with an 11% increased risk for dying from coronary heart disease or stroke at some point in the follow-up period of approximately 9.3 years, and getting more than that was associated with a 33% increase in risk.
Another study on sleep, conducted by a different team of scientists, was also presented at the European Society of Cardiology conference. Those researchers had people wear a waist-band monitor for one week to track their sleep patterns. The results suggested that people who got less than six hours of sleep per night or woke up frequently had about 27% more atherosclerosis: hardening in the arteries that can lead to blockage or narrowing and contribute to heart failure, stroke, or aneurysm.
Yet another new study presented at the cardiology conference reported on a group of 798 men from Gothenburg, Sweden, who provided information on how long they slept in a 1993 survey, when all participants were 50 years old. Twenty years later, the men who had said they slept less than five hours per night were found to have double the risk of a serious cardiovascular event. That increased risk for a heart attack or stroke is comparable to the effects of smoking or having diabetes.
Good reasons to get regular sleep
All of these new studies show an association, not a cause-and-effect relationship.
Pinpointing exact causal mechanisms is difficult, since a lack of sleep messes with our bodies in a number of ways that increase disease risk. One recent study, for example, found that not getting enough sleep changes genes in ways that promote obesity and impair metabolism. Other research has shown that sleep deprivation leads to inflammation, which may contribute to cardiovascular disease risk.
"More research is needed to clarify exactly why, but we do know that sleep influences biological processes like glucose metabolism, blood pressure, and inflammation — all of which have an impact on cardiovascular disease," Fountas said.
Overall, the new research gives us even more good reasons to make sure we sleep enough (but not too much) on a regular basis.
"Having the odd short night or lie-in is unlikely to be detrimental to health, but evidence is accumulating that prolonged nightly sleep deprivation or excessive sleeping should be avoided," Fountas said.