Do you really need a mattress protector?

You do not technically need one, but it is among the cheapest ways to protect a major purchase. A protector keeps spills, sweat, and allergens out of a mattress you cannot wash, extends its life, helps keep the warranty valid, and improves hygiene. Given how little it costs relative to a mattress, skipping one is a false economy. The main reasons to go without are if you already use an encasement or are testing a new bed during a sleep trial.