Sleeping on your back or face down may cause neurodegenerative illness, research finds.

A research on rats found that sleeping on our sides helps prevent neurological disorders including Alzheimer's, ALS, and Parkinson's. 

In a lateral (or side-sleeping) posture, glymphatic clearance is most effective. Gravity, compression, and stretching may be at blame.

This brain activity is usually off when we're awake but activates during sleep to distribute vital substances and remove poisonous waste.

Even flies need sleep to live. Whales and dolphins switch sleep between brain hemispheres to monitor for predators and breathe. 

A single night without sleep may increase brain harmful waste protein, according to PNAS research.

Lou Gehrig's disease (ALS) is the most prevalent motor neuron illness. ALS patients lose the capacity to talk, swallow, and breathe.