A koala sleeping in a eucalyptus tree, Australia

© Anton Rogozin/Getty Image

Koala sleeping in a eucalyptus tree

Take a cue from today's image; this sleepy koala may inspire you to catch some Z's. Despite being commonly called 'koala bears,' the koala is not a bear. Koalas are marsupials, a type of mammal that carries and nurses their young offspring in a pouch. These adorable Australian marsupials can sleep up to 20 hours a day, which helps them conserve the little energy they get from their eucalyptus-based diet. Koalas move slowly when awake, spend most of their time tucked into nooks in trees, and have a lower body temperature than other animals of their size. Koalas are herbivores and their diet consists exclusively of eucalyptus leaves. These leaves are very fibrous and difficult to digest, but koalas have a specialised digestive system that allows them to break down the tough cellulose in the leaves.