You may not have given much thought to your sleeping position, but the way you spend your night can have an impact on your overall health. Each position comes with its own pros and cons that you might want to consider next time you grab some shut-eye.

For example, sleeping face-up with a pillow under your back may help with back pain but may also worsen symptoms of sleep apnea. Sleeping on your side may be better for sleep apnea, but you may find that it hurts your spine.

If you’re dealing with a heart condition, you may want to avoid sleeping on your left side. It’s thought that sleeping on this side may reposition your heart in your chest and change its electrical activity. It’s still not clear if this effect is large enough to be of concern.

Keep reading to learn why sleeping on your left side may be bad for your heart. We’ll also look at the best and worst sleeping positions for people with heart conditions.

There’s little research examining the effects of sleeping positions on heart health. However, there’s some evidence that sleeping on your left side may increase pressure on your heart.

In 1997, researchers first noticed that side sleeping caused noticeable changes to the electrical activity of the heart measured with an electrocardiogram (ECG). The researchers found a more noticeable effect when the participants were lying on their left side.

In a more recent 2018 study, researchers also found that sleeping on the left side was associated with changes in ECG readings in healthy participants. Using a type of imaging technique called a vectorcardiography, they found that left-side sleeping caused the heart to shift and turn. The changes in electrical activity were attributed to this movement of the heart.

When the participants slept on their right side, almost no change in ECG activity was found. The researchers found that in this position, the heart was held in place by the thin layer of tissue between the lungs called the mediastinum.

Even though lying on your left side may change your heart’s electrical activity, there’s no evidence that it increases your risk of developing a heart condition if you don’t already have one.

Anecdotally, people with congestive heart failure often report discomfort and trouble breathing when sleeping on their left side. More research needs to be done to understand if sleeping on your left side is dangerous for people with heart conditions or how dangerous it may be.

There remains some controversy about whether sleeping on your left or right side is better for your heart. Some sleep experts think that sleeping on your right side could compress your vena cava. This is the vein that feeds into the right side of your heart.

However, at this time there’s no evidence that sleeping on your right side increases your risk of developing heart failure, and it seems to be safe.

A 2018 study found that the majority of participants with a heart muscle disease called consecutive dilated cardiomyopathy preferred to sleep on their right side rather than their left.

Also, a 2019 review of studies found no difference in the health of pregnant people or their unborn babies when sleeping on their left or right sides. Early in your pregnancy, try to get into the habit of sleeping on your side. Lying on your side with your knees bent is likely to be the most comfortable position as your pregnancy progresses.

Some doctors recommend that pregnant people sleep on their left side. Because your liver is on the right side of your abdomen, lying on your left side helps keep the uterus off that large organ and it also makes your heart’s job easier because it keeps the fetus’ weight from applying pressure to the large vein (called the inferior vena cava) that carries blood back to the heart from your feet and legs to improve blood flow to the fetus.

At this time, it’s still not clear what the best sleeping position is for your heart health if you don’t already have an underlying heart condition. Likely, getting quality sleep is more important than your sleeping position.

A 2018 review of studies published in the Journal of Clinical Sleep Medicine found that both poor sleep quality and short sleep duration are associated with a risk of coronary heart disease.

If you’ve had heart failure, you should speak with your doctor about any sleeping positions that you should avoid.

Sleeping on your right side may be the best option for people with heart failure. Although some people think sleeping on your right side could restrict blood flow back to the heart, there’s not enough evidence to prove that it’s harmful.

If you don’t have sleep apnea or any breathing problems, sleeping on your back may also an option for you.

A 2015 study examined the effects of lying face-up in participants with stable chronic heart failure. The researchers found that lying face up was associated with poorer blood oxygenation, respiratory mechanics, and blood movement compared to sitting.

Sleeping on your stomach may alleviate sleep apnea and snoring, but can also cause neck or back pain. Untreated sleep apnea is associated with an increased risk of heart failure, and many people deal with both.

If you have an implantable cardioverter defibrillator (ICD), you may find it more comfortable to sleep on the opposite side that it’s implanted. Most of ICDs are located on the left side.

It’s still not clear what the best and worst sleeping positions are for people with heart conditions. There’s some evidence that sleeping on your left side may shift your heart and disrupt your heart’s electrical current. Also, many people with heart failure report having trouble breathing in this position.

Sleeping on your back can worsen sleep apnea and snoring. You should speak with your doctor before sleeping on your back if you’re dealing with any breathing issues.

At this time, it’s still unclear what the best way to sleep is for your heart health. Anecdotally, many people with heart failure seem to find it more comfortable to sleep on their right side than their left side.

Although little is known about the best sleeping position for your heart, research has found that not getting enough sleep or getting poor quality sleep raises your risk of developing heart disease. Making sure you stay well-rested is important for maintaining optimal heart health, no matter the position in which you sleep.

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