Top 20 Animals That Sleep the Least
Explore the fascinating world of animals with the shortest sleep cycles!
Two hours is a long nap for us humans, but far too short for a restful sleep. For some animals, this is sufficient. They don't sleep more than two hours a day throughout their lives. They developed this behavior over time and it is part of their adaptation to their way of life and their habitat.
Some of these animals doze off for just a few seconds in one go. By the end of the day they have taken thousands of little naps.
Top 10 Animals - Shortest Sleep (per Day)
Here are the top 13 animals that barely sleep. According to the Guinness Book of Records in 2017, the elephant is the animal that sleeps the shortest. It only dozes for two hours a day. However, a scientific study from 2021 shows that the elephant seal only sleeps one hour a day.
Did you know that scientists have a hard time distinguishing real sleep from "sleep-like states" or, more accurately, "rest phases"? It is easier with mammals and birds, but with insects, amphibians, reptiles, fish and invertebrates it is a challenge. Some species can't close their eyes or have no pupils, which makes it harder to detect REM sleep in them.
In this table, the duration specified is always meant per day. It is the sum of all naps in one day.
| Species | Sleep per Day |
|---|---|
| Elephant Seal | 1 hour |
| Elephant | 2 hours |
| Okapi | 2 hours |
| Impala | 2 hours |
| Horse | 2-3 hours |
| Donkey | 3 hours |
| Deer | 3-4 hours |
| Giraffe | 4 hours |
| Sheep | 4 hours |
| Cow | 4 hours |
| Ant | 4-5 hours |
| Goat | 5-6 hours |
| Gray seal | 6 hours |
Top 10 Animals - Shortest Sleep (in One Go)
How long do animals sleep at a time? Or rather, let’s say: how short! Chinstrap penguins come for a total of 11 hours a day, but they only doze for a few seconds at a stretch. Why? They have to constantly keep an eye open because a predator might approach. In one day, they take 10,000 short naps that last no longer than 4 seconds.
Magnificent frigate birds can even sleep while flying - for a full 41 minutes. However, they don't sleep through, but take short naps that last no longer than 12 seconds.
The Alpine swift is a very unusual animal. It can fly for 200 days in a row without landing. That's well over six months. It eats while it is flying. It even sleeps during its flight - for a duration of few seconds at a time.
| Animal | Sleep Duration (at a time) |
|---|---|
| Chinstrap penguin | 4 seconds |
| Swift | 10 seconds |
| Magnificent frigate bird | 12 seconds |
| Ant | 1 minute |
| Giraffe | 5 minutes * |
| Deer | 5 minutes |
| Okapi | 5 minutes |
| Sperm whale | 10-15 minutes |
| Elephant | 15 minutes |
| Horse | 15 minutes |
| Dolphin | 2-3 hours |
* Up to 35 minutes
Animals That Stay Awake the Longest
Walrus
The animal that can stay awake the longest is the walrus. It is capable of being awake for 84 hours in a row. It can still swim actively during this time. After such a long time it needs to catch up on sleep. To “recharge the batteries,” it sleeps for 19 hours at a time.
Dolphins and Orcas
For the first few weeks of their lives, dolphin and orca calves don't sleep at all. They don't even take a little nap. After about a month they start to sleep for a few minutes. The duration increases very gradually. The reason behind this behavior: contrary to adult animals, they have less “blubber” (warming layer of fat). They have to constantly move to avoid freezing to death.
Bullfrog
The bullfrog was once believed to never sleep, but recent findings have cast doubt on this long-standing belief. At the time when the study was carried out, there were no advanced technological possibilities available yet. A new study would be necessary.
Sources:
- "Forced into an ecological corner: Round-the-clock deep foraging on small prey by elephant seals" (https://www.science.org)
- "Behavioral sleep in the walrus" (https://pubmed.ncbi.nlm.nih.gov)
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