Optimal sleeping position has been a topic that is riddled with a lot of conjecture, but with very little evidence to support anyone’s expert opinion. What we do have are a plethora of infographics like the one you see below created by the likes of Cleveland Clinic, The Huffington Post, and this particular one from the Wall Street Journal:

Sleep Infographic Credit WSJ vis The Best Infographics

I’ll be honest. I make the same recommendations in my practice because this is what I’ve been taught for a long time, and they do make sense from a biomchanical and physiologic basis. However, if you take a quick search through Pubmed, you won’t see much. A few articles about how back sleeping causes snoring and worsens sleep apnea, but that’s about it.

Building Theories with Sleeping Rats

A recent study in the prestigious Journal of Neuroscience provided some clues that may lead to some insight. The authors studied rats and mice using contrast MRI and studied their brains after death.

They were looking at a system called the Glymphatic System. For comparison’s sake, the glymphatic system is like a plumbing system for your brain. It helps get rid of waste products from your brain.

If you want a more in depth explanation on this interesting system, you can read about it in some of my other articles here:

Research: Dementia from Head Injury May Be a Plumbing Problem 

I’ll be honest, I don’t quite understand many of the methods used in the paper. The science is a little bit beyond my pay grade. But here’s what I have gathered from the summary and discussion section:

1. Side sleeping increases the effectiveness of the brain’s glymphatic (plumbing) system.
2. Sleeping on the stomach made this system less effective.
3. When the plumbing system doesn’t work as well, metabolic waste tends to remain in the brain.
4. The inability to remove metabolic waste (amyloid proteins, etc) is linked to dementia and Alzheimer’s Disease.

What Is Special About Side Sleeping?

Side sleeping is the most commonly observed, and commonly reported sleeping position in human beings. It is also the default sleeping position of most mammals including dogs, rats, and even elephants.

Scientists don’t really know why side sleeping is preferred, but they suspect that it has a lot to do with head positioning.  The authors also suggest that positioning may have a stretching or compressing effect on the nerves and blood vessels of the neck and trunk. When these vessels and nerves are compressed it can impact the autonomic aka automatic part of the nervous system. It’s the system that is responsible for controlling your heart, lungs, stomach, hormones, etc. All the stuff that you don’t think about (hence “automatic” nervous system because it’s on autopilot).

When you combine the altered nerve activity, with sluggish blood flow, then you have an effect on how the brain drains during sleep.

What Does this Mean for People?

This study can’t be generalized to people…..yet.

Rodent spinal anatomy and human spinal anatomy are pretty different, so we’ll see how this plays out.

Here’s what I do know from clinical experience:

1. People generally sleep better when I suggest a side lying sleep position. That includes musculoskeletal problems like back/neck pain and breathing problems like snoring.
2. In terms of Structural Chiropractic and NUCCA, head positioning makes a HUGE difference in someone’s overall sense of well-being.
3. When people have their head and neck corrected, one of the most common benefits is that they tend to sleep deeper and easier then they had in the past. Better sleep = healthier brain = more robust healing response.

In the end, sleeping position may not matter that much for most people. The most important thing to remember above all else, is that you get high quality, high quanitity, consistent, deep, restful sleep on a regular basis. If you have a choice of losing sleep with an “ideal” sleep position, you are better off choosing comfort over theory.