Not only understanding what an innerspring mattress is, but what type of coils are in these hybrid mattresses will only help you as you find the perfect bed to sleep on. You spend about 1/3 of your day in your bed. It is one of the most important things in your home and one that is responsible for how you sleep, how you feel and how the rest of your day goes. The more you know about innerspring mattresses as you shop, the better prepared you will be to make the right purchase for you so that you can literally sleep soundly each and every night.