Sleeping Positions & Your Heart & Brain

It’s Q&A Day at 10almonds!

Have a question or a request? We love to hear from you!

In cases where we’ve already covered something, we might link to what we wrote before, but will always be happy to revisit any of our topics again in the future too—there’s always more to say!

As ever: if the question/request can be answered briefly, we’ll do it here in our Q&A Thursday edition. If not, we’ll make a main feature of it shortly afterwards!

So, no question/request too big or small 😎

❝Is it true that sleeping on your left side is bad for the heart?❞

Short answer: it can be!

It has to do with how much room the heart has to move around.

Now, mostly we tend to assume that our organs stay put, but the reality is, they have quite a bit of leeway to move around (one of the reasons why sitting is so bad for the health; see: Death by Sitting – by Carolyne Thompson and for how to fix that besides “sit less”, check out Stand Up For Your Health (Or Don’t) ← our main feature on this also includes more things you can do if you must sit, to make sitting less bad!).

When it comes to our heart, this is broadly situated fairly centrally and/but a little to the left, behind our sternum. This means that when we sleep lying on our right-hand side, the pull of gravity on our heart is towards the center, where there the internal structure (namely the mediastinum) supports it and keeps it in place.

When we sleep lying on our left-hand side, however, the heart can squish downwards (i.e. to our left) a bit, which can affect how it beats:

Lying position classification based on ECG waveform and random forest during sleep in healthy people

For most people, this shouldn’t be a huge issue, as our heart (much like the rest of our body) is quite resilient, and capable of looking after itself. However, if one has a predisposition to certain kinds of heart condition, it can become more of a problem, and for everyone, it’s at the very least not ideal.

On the other hand (literally), sleeping on the left-hand side can be better to avoid acid reflux if that’s a problem for you, due to the orientation of the opening at the the top of the stomach.

Body position affects recumbent postprandial reflux

Meanwhile, the brain is also a consideration when it comes to sleep positions and health. Because the glymphatic system (glial cells doing the clean-up job of the lymphatic system, but in the brain, where lymph cannot go) is strongly affected by gravity, the brain’s ability to remove toxins is dependent on the orientation of the head. This is critical for avoiding Alzheimer’s (beta-amyloid clearance) and Parkinson’s (alpha-synuclein clearance) amongst others, and for this:

• sleeping sideways is far better than sleeping on one’s back.
• sleeping on one’s right side is better than sleeping on one’s left side.

For more details on that, see:

Goodnight, Glymphatic System: How Your Sleep Position Changes Dementia Risk

Take care!