Hibernation is more than sleep. It is a very deep sleep.The animal's temperature drops to just over zero centigrade, and its heart beats very slowly
People who find hibernating animals asleep often think that they are dead: the body feels very cold, and the creature may breathe only once every five minutes.A hibernating animal cannot feel any pain.You can touch it, or even pull its tail, without causing it to move or wake up.In its hibernating state it can even live in a poisonous atmosphere for a long time without any ill effect.