You can take over and control any animal for as long as you'd like. Your human self will be "asleep," but your conscious mind will be fully awake within the animal. You can choose to not feel pain, will know how to use all of the animal's bodily functions, and if the animal you're controlling dies, you'll be transported back into your body again. This ability excludes controlling other humans. To make matters better, the sleep you get while controlling the animal is good, quality sleep!