Is it true that sleeping on your left side is harmful to your health?

There is a widespread belief that the position of lying on the left side is the most dangerous for sleep, since in this position the heart and other internal organs work worse. We decided to check whether there is scientific evidence to support this fear.

Sleep is an important component of our life. According to calculations scientistsBy the age of 78, a person has spent as much as 25 years sleeping. Therefore, the question of the most useful sleeping position is extremely relevant. He cares users services with questions and bloggers. Many media outlets are turning to doctors in search of an answer: in particular, expert explanations have been published "Vesti.Ru", TV channel "Zvezda", "Gazeta.ru" And "Moscow 24". The harm of sleeping on the left side explain like this: “When you lie on your left side, the heart experiences stress from compression by the mediastinum and lungs.” However, there is no unanimity on this issue, and other experts, on the contrary, called the advantages of this position: “When a person sleeps on his left side, the functions of the digestive system are activated, which has a beneficial effect on health. In addition, metabolic processes improve.”

Sleeping on your side - the most common sleeping position. It is statistically more common than sleeping on your back or stomach. One of the earliest studies of different sleep positions was conducted in 1997. Scientists used an electrocardiogram (ECG) to monitor the electrical activity of the heart. A total of 40 people took part in the study, of which 18 were diagnosed with heart problems. It turned out that the position on the left side led to the most significant deviations in the ECG in those who had heart disease. At the same time, the scientists’ conclusions concerned only the observation of various segments of the ECG itself, and not the long-term consequences for the health of the subjects.

In 2018, Chinese specialists held similar study design. Nine healthy volunteers took part in it, and an ECG was also taken from them during the entire eight-hour sleep. Scientists noticed similar changes in the ECG graph itself, most clearly manifested precisely in the position of lying on the left side. In addition to ECG, another observation method was used - vector cardiography. He showed that the heart shifted slightly relative to its usual position when sleeping on the left side, while on the right side there was no displacement, since the organ was supported by the mediastinum (lungs, pleura, sternum and ribs). However, as in the first study, the findings did not address either the short-term or long-term health effects of sleeping on the left side. 

Also in 2018, another study, in which people with heart failure took part. It showed that the subjects themselves preferred to sleep on the right side, and the position on the left side was associated with the appearance of shortness of breath and other unpleasant symptoms. Scientists relied on subjective reports from subjects and echocardiography data. And although the patients considered lying on the right side to be a more comfortable position, scientists were unable to explain the reasons for this preference at the physiological level. 

At the same time, our brain is able to choose the most suitable pose itself. Scientists held polysomnography with body position monitoring on a group of volunteers: 75 of them were diagnosed with chronic heart failure (CHF), and the other 75 did not have heart problems. It turned out that patients with CHF themselves unknowingly spend significantly less time on their left side than healthy people. Thus, apparently, the brain itself is able to understand which position is now the most optimal, and give the body a signal to accept it. 

However, sleeping on your left side may have its advantages. So, sleep specialist Christopher Winter in an interview with CNN notes: Sleeping on your left side "can promote blood flow to the heart," which can improve your overall well-being upon waking. Winter also focuses on the fact that left-sided sleep will be useful for pregnant women - this way the fetus puts less pressure on other organs, thereby not disrupting either its own or the woman’s blood circulation.

Experts from Johns Hopkins University (USA) too advise sleep on the left side for those who suffer from heartburn, as well as for pregnant women facing reflux disease. By choosing the left side as the main sleeping position, they can significantly reduce discomfort.

Side sleep on either side preferable for those who are prone to snoring, apnea (a breathing disorder in which a sleeping person stops breathing for short periods), and also experiences pain in the spine. Moreover, according to preliminary dataAccording to an experiment on mice, sleeping on one's side compared to other positions reduces the risk of developing Alzheimer's disease, Parkinson's disease and other neurological diseases.

Thus, there is not a single study that demonstrates that sleeping on the left side leads to heart problems in healthy people or worsens the course of cardiovascular diseases. At the same time, a large-scale cohort study, which included more than 60,000 people, showed that poor sleep quality, namely interrupted sleep or difficulty falling asleep, as well as chronic lack of sleep, can significantly increase the risk of coronary disease.

Not true

What do our verdicts mean?

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