Preferably you should sleep on one pillow. Why? Too many will flex your head forward when you are on your back. It will crank your head sideways to the ceiling when on your side. No pillow or a pillow too thin will do the opposite.
And, on your back, it won’t support the healthy neck curve! So use on pillow but make sure it’s a neck pillow that fits your body size.

Additional Reading Resources:
- Your Pillow may not be right for you
- Use my Neck Contour Pillow or my regular pillow?
- How the arc4life pillow helps a pinched nerve in the neck
- A Chiropractic Pillow that helps to promote good posture.
- For a Deep Sleep State, You do need to be sleeping with the Right Pillow


