High in the eucalyptus trees of Australia, koalas (Phascolarctos cinereus) are often seen curled into tight, fluffy balls, barely moving for hours at a time.
Visitors to wildlife parks sometimes joke that they must have arrived on a “sleepy day” because the koalas never seem to wake up.
So is that just bad timing, or do koalas really spend most of their lives asleep?
Verdict:
True
As surprising as it might sound, this claim is absolutely true.
Koalas are among the sleepiest mammals on Earth, typically resting for 18 to 22 hours a day. In other words, they are awake for only a small fraction of each 24-hour cycle.
This extreme sleep schedule isn’t laziness — it’s survival.
Koalas feed almost exclusively on eucalyptus leaves, a food source that is low in nutrients, high in fibre, and full of toxic compounds. Digesting these leaves demands a great deal of effort and time, yet provides very little energy in return.
To cope, koalas have evolved a slow metabolism and conserve as much energy as possible. Sleeping for long stretches helps them minimise movement and preserve precious calories.
When they are awake, koalas are usually feeding, slowly chewing leaves, or moving carefully between trees. Most of this activity takes place at night or during the cooler hours, making koalas largely nocturnal.
During the day, they remain still in the forks of trees, sleeping or resting to avoid heat and further energy loss.
It may look like a permanent nap, but for koalas, spending most of the day asleep is simply part of survival.
References:
1. National Geographic: Overview of koala behaviour
https://www.
2. Reference.com: Facts About Koalas — Habitat, threats and why they’re now endangered
https://www.reference.com/
3. Australian Geographic: Fact file Koala
https://www.
