How many pillows should you have?

It depends! 

The numbers of pillows you should have is up to you, and depends on your personal preferences and sleeping position. There are some general guidelines though:

• One pillow for your head: This is the most common recommendation for maintaining proper spinal alignment. And think about how you sleep for what pillow for this support. 
• Additional pillows for support: You may want to use additional pillows for support between your knees, under your back, or for other comfort needs.   
• Sleeping position: Side sleepers often benefit from a pillow between their knees to align their hips and spine. Back sleepers may want a pillow under their knees for additional support. Stomach sleepers may not need a pillow at all, or may prefer a very thin pillow.   

Ultimately, the best way to determine how many pillows you need is to experiment and find what feels most comfortable for you.