Achieving the right amount of quality sleep is an essential part of maintaining the overall health and well-being of most species. However, not all animals require the same amount of napping; some are drowsier than others, depending on their energy levels and sleep patterns. In honor of Earth Day, here are some of the world's sleepiest critters.

Sloths

Despite their reputation, sloths are surprisingly NOT the sleepiest animals. Though they have been recorded to sleep 15-18 hours a day in captivity, recent studies have shown they are more likely to get around 10 hours in the wild; nevertheless, the stereotype of laziness still fits.

Koalas

Reported to sleep up to 22 hours daily in captivity, koalas spend over 90% of their lives asleep. In the Australian wild, that figure may be closer to 14.5 hours of sleep daily, boosted by five additional hours of inactivity. Koalas enjoy eucalyptus leaves, which are low in nutrition, high in fiber, and full of toxins. For this reason, it takes more energy to digest safely, making a good deal of rest essential.

Brown Bats

Being nocturnal certainly has its benefits. Brown bats clock 19.9 hours a day asleep and are known to hibernate half the year due to a lack of food, spending this time hanging upside down in caves.

Owl Monkeys

Known as the “night monkey,” this creature also benefits from a nocturnal nature and sleeps up to 17 hours. Their name makes an obvious allusion: big brown eyes help them see more clearly in Central and South American forests at nighttime.

Squirrels

It may seem counterintuitive for such an active, scurrying animal, but squirrels sleep up to 14.9 hours a day – usually in nests built of twigs, leaves, and pine needles. It’s not a Tempur-Pedic, but in the wild, it will do!

Cats

You can always count on a cat to nap. They are cathemeral, taking quick, irregular rests all day so they can eat whenever it suits them. Giant cats reign supreme in the feline sleep rankings, with predatory lions and tigers getting up to 14-16 hours daily. House cats are not far behind, averaging about half their day asleep.

Mice

The pocket mouse may be tiny, but its need for sleep is great! Snoozing a little over 20 hours a day, they rank among the most rested creatures in the animal kingdom. As an added bonus, the extended hours in their burrows help them to avoid predators.

Armadillos

At anywhere from 18-20 hours of sleep, the armadillo is hard to beat in the nap department. However, this consists of hours spent in underground burrows, with little evidence that most of this time is spent sleeping. Nonetheless, imagine spending 20 hours a day in your bed!

Human Babies

As a species, humans are impressively tired – especially infants – sleeping up to 16 hours, two-thirds of our young lives. This is essential for processing new experiences, making memories, and developing a brain. Naturally, these hours come at a price; new parents can expect to lose around 600 hours (about three and a half weeks) of rest in the baby’s first year.

Sleep is an essential function of the natural world – and most creatures, whether big or small, need sleep to repair and recuperate. Don’t forget to make quality sleep a priority for yourself in the coming months!