It’s very normal for a chinchilla to sleep on its side. Chinchillas sleep on their side because of the following reasons: it's pregnant, its drained after a vigorous exercise, is feeling hot, or it simply loves sleeping in that position. Some chinchillas sleep on their side when they feel relaxed and content. Most of the time, a chinchilla sleeps on all fours, although sometimes it would sleep on its side. All these will depend on your chinchilla’s personality and behavior.