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Which Side Is Best To Sleep On: Left Or Right?

The side you sleep on can open you up to acid reflux or breathing difficulties.


Rachael Funnell


Rachael Funnell

Digital Content Producer

Rachael is a writer and digital content producer at IFLScience with a Zoology degree from the University of Southampton, UK, and a nose for novelty animal stories.

Digital Content Producer

sleep on left or right side
Should you sleep on your left or right side? Image credit: Fizkes /

Sleep can be remarkably difficult to get in these stressful times, so when you catch a few Zzzs it pays to get the best quality you can. While everything from avoiding blue light to reading and counting sheep has been touted as a tool for drifting off, the position we sleep in can also have a pivotal effect on its quality and our health.

Pillows can improve your sleeping position by better aligning your neck and back to ease pressure on your spine. Switching sides can also carry health benefits. This begs the question: which side is best to sleep on, your left or right?


In favor of the left

The majority of humans' stomachs sit on the left of the abdomen. So, when you sleep on your left side, its contents are more likely to stay put with the aid of gravity. Roll onto your right side and the raised position of the stomach may put you at a higher risk of experiencing acid reflux, though this won’t necessarily be true of everyone.

Acid reflux occurs when the stomach's contents works its way back up the esophagus, causing a burning and gnawing sensation which can cause significant discomfort and even lead to the formation of ulcers. Giving your body some time to digest meals before lying down is one way to reduce your risk of experiencing acid reflux – but if you’re a right-sided sleeper, waking up with acid reflux switching to the left could make a difference.

In favor of the right

While the left appears to be a good choice for people with certain gastric issues, sleeping on the right side has been linked to easier breathing for people who experience sleep apnea. Research in 2011 took a group of people with the condition and assessed how left-side versus right-side and back sleeping compared in terms of severity of breathing difficulties.

“We found that the sleeping position had a significant influence on apneic events and [right-sided sleeping position] decreased the frequency of obstructive respiratory events in patients with moderate and severe disease,” concluded the paper’s authors.


The exact mechanisms for the association of right-sided sleep with better breathing aren’t entirely clear, but were further studied in a 2018 study that looked at echocardiographic changes in sleep positions. They found that patients with heart failure preferred right-sided sleeping, possibly a self-protecting mechanism to improve cardiac function that the person doesn’t even realize they’re doing.

What about face-down or on your back?

In the case of Left v Right, it seems there are conflicting arguments depending on your health. However, in the case of sleeping face down, things appear to be a little more clear cut. Sleeping face-down (or prone, as science calls it) causes a significantly higher increase in intraocular pressure (fluid pressure in the eyes) compared to side sleeping, something which can lead to glaucoma, optic neuropathy, and sight problems.

Sleeping face-down is also more likely to impact your skin, putting you at higher risk of developing wrinkles compared to alternative positions which put less pressure on your face. Known as sleep lines or sleep wrinkles, they form as a result of tension from our pillow, and where compression and tension meet as gravity and resistance make our faces smush.

On average, we switch sleep position 20 times throughout the night, and the longer we spend in one spot the greater the chance of it impacting our skin. Sleep wrinkles tend to form in slightly different places compared to those we get from facial expressions. While sleeping on your back is the best way to avoid them, the supine position can lead to difficulty breathing, leading to snoring and sleep apnea.

Getting help

It's perhaps easy to see, upon reflection, why drifting off can be so difficult when there are so many conflicting factors at play in which position is going to keep you comfortable and healthy while you conk out. 

As always, if you’re experiencing issues with pain, breathing, or digestion, it’s best to speak to your health care provider – but ensuring you’ve got a good sleeping set up and are shaking up your position throughout the night can go some way to improving your Zzzs.

All “explainer” articles are confirmed by fact checkers to be correct at time of publishing. Text, images, and links may be edited, removed, or added to at a later date to keep information current. 


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  • sleep,

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  • digestion,

  • glaucoma,

  • wrinkles,

  • sleep apnea,

  • acid reflux