Dormice breed one or two times per year, having an average of four young after a gestation period of 21–32 days. Dormice can live for as long as five years. The young are born without hair and they cannot do anything for themselves. Their eyes do not open until about eighteen days after birth. They are usually ready to reproduce after the end of their first hibernation. Dormice live in small family groups. The area they live in depends on which species they are, and how much food is available.