At night, your brain activates the glymphatic system — a “clean-up crew” that flushes out waste like beta-amyloid (linked to Alzheimer’s)
A 2015 study in the Journal of the American Society of Nephrology found that lateral sleeping (especially on the left) may enhance glymphatic flow compared to back or stomach sleeping
The left side may improve fluid drainage due to the position of the brain’s waste-clearance pathways

✅ While more research is needed, side sleeping is already linked to better brain health.

2. Aids Digestion & Reduces Acid Reflux

Your stomach sits on the left side of your abdomen
When you sleep on your left side, gravity helps keep stomach acid below the esophagus, reducing heartburn
The duodenum and pancreas also drain more efficiently in this position

✅ A 2011 study in The American Journal of Gastroenterology found that left-side sleepers experience less acid reflux than right-side or back sleepers.

3. Supports Heart & Circulation Health

The heart’s aortic arch and lymphatic system are on the left side of the body
Sleeping on the left may:
- Improve lymphatic drainage (which filters toxins)
- Support venous return (blood flow back to the heart)
- Aid spleen function (which filters old blood cells)

✅ Especially beneficial for those with heart failure or edema (though always consult a doctor).