My spiney mice like to cuddle up together when they sleep to keep warm. This is what they would do in the wild. For some reason Buttercup my smallest female likes to sleep on top of her sister, sometimes back to front. It looks like Blossom is wearing a bizarre nightcap...the expression on her face looks like she's not that impressed. I don't think anyone really wants to sleep with a bum right in their face! I like this picture partly because it makes me laugh, and partly because you can see the amazing 'hedgehog spines' very clearly.