What is hibernation?

Hibernation is a state where animals slow down their metabolism to use as little energy as possible over the winter, when food is scarce.

Their heart rate drops, as does their breathing, and they survive on fat stores built up over the summer.

It’s called hibernation rather than sleep because the brain cycles the animals go through are different.

It’s more of an extreme slowing down but only three British mammals truly hibernate – bats, hedgehogs and dormice. Birds have either adapted to the season or migrate, while reptiles go into a state called brumation.