The last time I went to bed without a hair bonnet, I woke up to find my pillowcase covered in hair oil (bad for my skin) and my hair a hot, frizzy mess (bad for, well, me). Not to sound dramatic, but hair bonnets are as essential as oxygen. Wrapping your hair up in a protective cap helps to extend the life of protective hairstyles, fight frizz, and retain moisture while you get your zzzzs in. Sleeping without one can dry your hair out, cause breakage, and force you to buy even more hydrating shampoos and moisturizing conditioners to reverse the damage. Silk or satin bonnets provide all those benefits wrapped up in plush, soft fabric that makes styling your hair the next morning a more seamless process. You can never have too many bonnets, so here are 11 of the best bonnets to keep your hair happy, healthy, and hydrated.