That’s a huge difference. Animals that Sleep the Least | Sleep.org. Top 10: Which animals sleep the most? Below are 10 animals (including human) that require longest sleeping hours per day. Read more: Top 10: Which animals have the strongest bite? Top 10: Earth’s smallest mammals; Advertisement. Subscribe to BBC Focus magazine for fascinating new Q&As every month and follow @sciencefocusQA on Twitter for your daily dose of fun science facts. The most sleepiest animal in the world can sleep about 22 hours (out of 24) and animal that sleeps the least (giraffe) only 1.9 hours. Walruses: These guys may look sleepy in photos or at the zoo, but they can actually go for up to 84 hours straight without a single minute of sleep.