Who Sleeps For 90% Of The Day?: Most Surprising Answer

Koalas and some sleeping bats can rest for up to 20–22 hours a day, roughly 80–92% of the day.

I’ve studied wildlife and cared for rescued animals, so I know why people ask, “Who sleeps for 90% of the day?” This article breaks down which creatures come closest to that extreme, why they sleep so much, what it means for their health and survival, and practical lessons for caring for sleepy animals. Read on for clear, well-researched answers and real-world insights.

Which animals come closest to sleeping 90% of the day?

Many readers mean to ask, “who sleeps for 90% of the day?” when they picture tiny, motionless animals. The top contenders are:

• Koalas: Often cited first. They commonly sleep 18–20 hours per day. In some cases they may reach levels near 90% of the day.
• Certain bats: Some species sleep for long stretches, sometimes 18–20 hours daily.
• Slow lorises and some small marsupials: They also show very long sleep times compared to other mammals.
• Newborn mammals and birds: Babies can sleep almost constantly while they grow.

These animals don’t all sleep exactly 90% of the day every day. Instead, some individuals or species can reach that level at times. If you ask, “who sleeps for 90% of the day?” the most accurate short answer is that koalas and certain sleeping bats are the closest wild examples.

Why do some animals sleep so much?

When people ask “who sleeps for 90% of the day?” they want the reason. The main causes are:

• Energy conservation: Animals with low-calorie diets sleep more to save energy.
• Digestive needs: Slow digestion and a heavy gut can take energy, so rest helps.
• Predator avoidance: Staying still reduces detection by predators.
• Metabolic rate: Smaller or slower metabolisms can be linked to long rest periods.
• Development and repair: Babies and animals recovering from stress sleep to heal.

These reasons are backed by animal behavior studies. The exact mix of causes varies by species.

How sleep patterns differ across species

Sleep is not the same for all animals. Think about it this way:

• Light vs. deep sleep: Some animals nap lightly and wake easily. Others have long deep sleep.
• REM vs. non-REM: REM sleep varies widely. Some animals have little REM and still rest a lot.
• Fragmented sleep: Bats and some birds sleep in many short bouts. Koalas often sleep in long stretches.

If you are wondering “who sleeps for 90% of the day?” remember that total hours are only part of the story. The type and timing of sleep matter, too.

Practical examples and typical sleep times

Here are simple, real-world numbers that answer “who sleeps for 90% of the day?” more clearly:

• Koala: 18–20 hours per day. Some individuals may hit 21–22 hours when food quality is low.
• Little brown bat (and similar species): 18–20 hours during roost periods.
• Opossum: Around 18 hours in captivity or safe habitats.
• Newborn kittens and puppies: Up to 20 hours while growing.

These examples show who sleeps for 90% of the day in the sense that some animals may reach or approach that level under certain conditions.

My experience: working with very sleepy animals

I’ve spent time volunteering in wildlife rehab. I have seen koalas tucked high in gum trees asleep for long stretches. I have also cared for newborn mammals that needed nearly constant sleep. From that work I learned:

• Do not wake sleeping wild animals; it stresses them and uses needed energy.
• Provide quiet, dark, and safe spaces for animals that naturally sleep a lot.
• Monitor food quality: poor diet often increases sleep time dramatically.

These small lessons help protect animals that approach the extreme end of sleep.

What this means for pet owners and conservation

If you ask “who sleeps for 90% of the day?” for pets, know that common pets rarely sleep that much. Still, long sleep can signal:

• Natural behavior: Some pets nap a lot by nature.
• Health issues: Sudden or prolonged increases in sleep call for a vet visit.
• Habitat needs: Wild animals that sleep most need safe, low-stress environments for survival.

For conservation, protecting habitat and food sources reduces the need for extreme energy-saving sleep. That helps species stay healthy and reproduce.

Signs of healthy versus concerning sleep

Look for these signs:

• Healthy: Regular sleep-wake cycles, good appetite, normal weight.
• Concerning: Lethargy with poor appetite, odd breathing, or inability to wake.

If a pet or an animal in rehab seems to sleep far more than expected, consult a professional.

Frequently Asked Questions of Who sleeps for 90% of the day?

Who exactly sleeps for 90% of the day in the wild?

No species sleeps exactly 90% habitually, but koalas and some bats can reach sleep levels near 90% under certain conditions.

Do baby animals sleep 90% of the day?

Many newborns sleep up to 20 hours a day while they grow, so they can come close to that percentage for a time.

Can pets sleep for 90% of the day?

House pets rarely sleep that much. If they do, it may indicate illness or stress and a vet check is wise.

Why do koalas sleep so much?

Koalas eat low-energy eucalyptus leaves. Their slow digestion and need to conserve energy drive long sleep times.

Is sleeping 90% of the day harmful?

Extended sleep can be natural for some species or life stages, but for most animals it signals low activity and may hide health problems if sudden.

Conclusion

Animals that sleep nearly all day remind us that sleep is a survival tool. Koalas and some bats are the best real-world answers to “who sleeps for 90% of the day?” but many factors shape extreme sleep—diet, metabolism, safety, and life stage. If you care for animals, respect their rest, watch for sudden changes, and seek expert help when sleep patterns shift. Want to learn more about animal sleep or share your own observations? Leave a comment, subscribe, or explore local wildlife rehab programs to see this behavior up close.