By Alice || Edited by Go Ask Alice Editorial Team || Last edited Feb 16, 2024
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Alice! Health Promotion. "Is it harmful to sleep on my side?." Go Ask Alice!, Columbia University, 16 Feb. 2024, https://goaskalice.columbia.edu/answered-questions/it-harmful-sleep-my-side. Accessed 24, May. 2024.

Alice! Health Promotion. (2024, February 16). Is it harmful to sleep on my side?. Go Ask Alice!, https://goaskalice.columbia.edu/answered-questions/it-harmful-sleep-my-side.

Dear Alice,

Hi there.

Is sleeping on our left side in any way harmful for the heart (or anything else)? Some people tell me we shouldn't do it and others tell me it's actually better than sleeping on our right side. What's the truth?

Thanks!

Dear Reader, 

No one likes waking up on the wrong side of the bed! If you do, however, here’s some good news to lift your mood: there’s no evidence that sleeping on the left side is harmful to the heart if a person doesn’t have any underlying heart issues. In fact, sleeping on the left side—or sleeping on your side in general—can be beneficial for some people (more on this later). As long as you’re waking up comfortable and well-rested, there isn’t much reason to worry about your sleeping position. 

You might be wondering: where did this belief that sleeping on the left side is bad for the heart come from? Some research studies have found that sleeping on the left may alter electrocardiogram (ECG) readings in healthy participants. One possible explanation for this is that sleeping on the left side causes the heart to shift positions due to the pull of gravity. This movement may cause changes in the heart’s electrical signals. In addition, studies have found that patients with congestive heart failure tend to avoid sleeping on their left side. This has led some researchers to believe that the patients’ bodies may be trying, on some level, to protect their weakened cardiovascular system by switching to right-side sleeping. Although sleeping on the left side may alter the heart’s electrical activity, there’s no evidence to suggest that this increases a healthy person’s risk of developing a heart condition. More research is also needed to understand how sleeping on the left side affects people with heart conditions. 

Side sleeping is the most common position that people catch their z’s in. Sleeping sideways takes pressure off the spine, making it a comfortable position for many people. In some cases, side sleeping is even recommended. It offers several benefits that make it suitable for: 

  • People with back pain: Side sleeping takes the pressure off the spine and keeps it in healthy alignment. 
  • People who snore or have sleep apnea: Lying on the side helps to keep the upper airway open. It prevents the uvula (the fleshy bit that hangs at the back of the throat) from moving backward and obstructing the throat, making it easier to breathe. 
  • People with glaucoma: Lying sideways puts pressure on the eye that is facing downwards. Hence, it’s recommended that people with glaucoma sleep on the opposite side of the affected eye. 

Sleeping sideways has its perks, but what should you do when there are two sides to choose from? Whether sleeping on the left or right side is better depends on your health condition and needs. For instance, sleeping on the left side may be beneficial for: 

  • People with acid reflux: Patients with gastroesophageal reflux disease (GERD), also known as chronic acid reflux, report fewer symptoms when sleeping on the left side. One possible explanation is that sleeping on the left side positions the stomach below the esophagus. This position keeps the level of gastric acid in the stomach below the opening to the esophagus, making it harder for gastric juices to flow back up into the throat. 
  • People who are pregnant: Lying sideways helps the heart to pump blood around the body more easily without the weight of a growing belly pressing down on the body. In particular, sleeping on the left side takes pressure off the liver and improves blood flow to the fetus, uterus, kidneys, and heart. 

While most people are side sleepers, sleeping on the back is also a popular position. Lying flat on your back keeps your spine straight and distributes your body weight evenly, which may be beneficial for people with lower back pain or neck pain. If you have a stuffy nose, sleeping with your upper back propped up can also help to keep the airways open and drain nasal passages.

The safest position to sleep in is one where you’re comfortable, able to get a good night’s rest, and aren’t waking up in discomfort or pain. For more information on different sleeping positions and tips to avoid tossing and turning, consider checking out the Go Ask Alice! archives. The best position to snooze in is the one that you snooze best in!  

Additional Relevant Topics:

General Health
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