Not everyone should sleep on their left side — leading sleep doctor explains why

A woman with dark hair sleeps happily on her left side
(Image credit: Getty Images)

If you sleep on your side, you’re definitely not alone. A 2019 study by Curtin University revealed that 60% of people habitually sleep on their sides. But which side should you sleep on: left or right? And is there a better side for sleep if you're pregnant, have acid reflux or other digestion issues, or you snore?

To get answers, we spoke with Dr Michael Breus (MD, FAASM), world-renowned sleep expert and the founder of The Sleep Doctor. As Dr Breus explains, sleeping on your left comes with its own pros and cons as does sleeping on your right side, but there is generally one side that most of us should sleep on for better health. 

Whether you sleep on your left or right, it’s important to invest in the best mattress for your body and sleep position, as an uncomfortable bed will quickly derail your sleep at night. For now, here's Dr Breus's take on which side you should sleep on...

Should you sleep on your left side?

Sleeping on your left side comes with lots of benefits, including easing heartburn and indigestion. That's because your digestive systems operate from right to left. “The large intestine wraps across our abdomen, from our right side to our left, and that is the direction food would go to get absorbed by the lower intestine," explains Dr Breus. “Sleeping on the left facilitates this movement, helping food to be digested more efficiently, basically due to gravity.”

Another positive of sleeping on your left side is the potential to reduce snoring or sleep apnea. While sleeping on either side alleviates snoring and sleep apnea better than back and stomach sleeping, Dr Breus, reveals that left-side sleeping can be even more effective — and it’s all to do with the tongue. “By sleeping on one side it forces the tongue to fall forward, “ he says. “Not backward, avoiding sleep apnea."

A man with dark hair rolls his eyes in frustration and holds a pillow to his ears because his partner is snoring

(Image credit: Getty)

According to The Sleep Doctor, the final reason you should sleep on your left side is one you may not have heard before: sleeping on your left side helps reduce Alzheimer's. Dr Breus explains that the glymphatic system (or “the brain’s waste management system”) is most active when we’re at a certain stage of sleep. 

“During stage 3/4 of sleep the glymphatic system goes in and scoops out proteins that are harmful.” While Dr Beus says the reason is unknown, research has shown that this entire system works better when you sleep on your left side.

So to recap, the benefits of sleeping on your left side include:

  • Better digestion
  • Reduction in acid reflux
  • Reduction in snoring
  • Reduction in sleep apnea
  • Lower risk of Alzheimer's
  • Better circulation during pregnancy

Should you sleep on your right side?

So we’ve seen that sleeping on your left hand side has a tonne of benefits, but what about sleeping on your right side? “I think this is really more for people with heart conditions,” reveals Dr Breus. ”Studies show that many people with heart failure naturally choose to sleep on their right side and avoid sleeping on the left side.”

He explains that sleeping on the right side can add more comfort when sleeping with heart failure, as shown in a 2018 study. “Echocardiograms of people with heart failure show that left side sleeping impacts the way the heart functions,” says the sleep specialist. “Potentially causing discomfort.”  

Can you train yourself to sleep on your side?

While each side comes with its advantages, what happens if the side you naturally choose to sleep on isn’t the side that can alleviate your condition? Is there a way you can train yourself to sleep on the side that suits your condition better” According to Dr Breus, there is a way: “I use ankle and wrist weights with my patients and they seem to work well.”  

Frances Daniels
Sleep Staff Writer

Frances Daniels recently joined the Tom's Guide team as Sleep Staff Writer, and her role includes covering all sleep and mattress news, in addition to mattress reviews and buyer's guides. Frances is a PPA-accredited journalist and is hugely interested in the relationship between good sleep and overall health. When not writing about sleep and mattresses for Tom's Guide, Frances enjoys writing about women's issues, health and wellbeing, the environment, and her native Wales.