A scrunchie :)

The multi purpose accessory for sleeping.
Sleeping with you hair pulled back in a scrunchie is good for you hair because it can prevent your hair being pulled and broken as you roll around in your sleep. A scrunchie in particular is good because it is gentle and won't split or break your hair :)
Secondly your hair is very absorbent and can collect anything from the air throughout the day, for instance cigarette smoke or any kind of dirt. If your skin is spot prone especially, having hair on your face can cause breakouts. When you can, keep hair off your face to eliminate this. Use a scrunchie :)
I have one scrunchie I kept from being a young child, my santa one :D