Living primarily in the Southern Hemisphere, with the Galapagos penguin as the only exception found north of the equator, penguins have caught the hearts of many.
Thanks to their monogamous characteristics, ocean flying, and adorable wobble when they walk, the 19 species that make up the penguin family are adored.
Although these cute birds can’t fly, they have adapted to thrive in their specific locations.
But have you ever wondered how they sleep?
Penguins have unusual sleeping patterns. Instead of sleeping for an extended period of time, they take short naps throughout the day and night, either lying down or standing.
If the strange sleeping pattern of these birds intrigues you, the following may give you some insight into how penguins sleep.
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How Do Penguins Sleep?
As mentioned above, penguins don’t have a regular sleep pattern.
With humans and most predatory mammals, a steady sleep cycle is maintained.
Either sleeping at night with the day being our active hours (diurnal) or sleeping in the day and being active at night (nocturnal).
Penguins, however, not only sleep during the day and night, but instead of falling into a prolonged deep sleep, penguins take periodic naps.
The length of these naps varies, depending on species, location, time of year, and safety factors.
Do Penguins Sleep Standing or Lying Down?
As with most of the sleeping habits of penguins, their sleeping position also differs according to species and location.
Most species of penguin can be found sleeping standing up, but this doesn’t mean it is their sole sleeping position.
Penguins found in icy environments tend to sleep the majority of the time standing up. This is believed to be because it limits their exposure to the icy floor, thus preventing heat loss.
Sleeping standing up also makes huddling easier and more efficient.
That said, penguins are also commonly found lying down.
Species such as the king penguin favor lying on their bellies when they sleep, while African penguins tend to sleep lying down in burrows.
Penguins, like all birds, need to feel safe before they fall asleep.
Ultimately, penguins will sleep in a position that is comfortable, warm, and safe.
Why Do Penguins Sleep in Groups?
There is no conclusive evidence as to exactly why penguins huddle and sleep in groups, however, there are two common theories that are followed.
The first is the one briefly mentioned above, for safety. As with many hunted animals, safety is found in numbers, and penguins are no different.
With large colonies, individuals are difficult to spot and single out, especially when tightly huddled together.
The second theory is for warmth, which is better backed by research.
Even with their array of fluffy feathers, birds still get cold, especially those that live on the ice. Although birds are warm-blooded, when exposed to extreme conditions, penguins need assistance to not freeze to death.
One paper found that when tightly huddled, the ambient temperature around the birds rose from -17 C to above 0 C. In extremely tight huddles the temperature rose to almost 37.5 C which is close to that of the penguin’s body temperature.
This makes not only for a cozy sleep but one that is warm and safe.
Do Penguins Sleep With Their Eyes Open?
If you are fascinated by penguins then it’s likely you’ve come across someone speaking about penguins sleeping with their eyes open.
We know that birds such as owls sleep with their eyes open, but is this the case for penguins, and can they sleep with their eyes open?
Yes, some species of penguins such as the emperor penguin and Humboldt Penguin sleep with one eye open. Surprisingly, unilateral eye closure is common among many animals such as birds, aquatic mammals, and reptiles.
Unihemispheric sleep, which puts one half of the brain to sleep and the other awake, is a defense mechanism that allows the animal to remain vigilant while resting. This allows them to not only stay visually but keeps their brains aware of predatory sounds.
Other animals that sleep with their eyes open include sea lions, parrots, fruit bats, crocodiles, and beluga whales.
Why Do Penguins Tuck Their Heads Away When Sleeping?
If you have ever seen a penguin sleeping, you will likely have noticed that like many other birds, they tuck their heads under a wing while sleeping.
Some scientists believe that this is a method used to keep in body heat, while others claim that it has no function and is simply a habit passed down through evolution.
How Long Do Penguins Sleep?
As you have likely well established by now, the sleep pattern of penguins differs greatly from what we are used to in our own lives.
Different sleep patterns can be classified as:
- Monophasic sleep: Individuals sleep only once per day for an extended period. The circadian rhythm of humans encourages extended sleep, which makes us monophasic.
This, however, is argued to not be our normal state, but rather induced by the industrial revolution and extended working hours.
Less than 14% of animals are truly monophasic.
- Biphasic sleep: Individuals split their sleep into two segments. Usually at night and in the afternoon. Many humans have adopted this sleep method.
Biphasic sleep is also known as segmented sleep and is performed by animals such as humans and some primates.
- Polyphasic sleep: Polyphasic sleep refers to a sleep pattern that is broken into multiple short “naps”. This is very common for birds, reptiles, and commonly hunted mammals.
Penguins, like most birds, fall into the polyphasic category.
There is no way of telling exactly how long penguins sleep, but what we do know is that they get their rest in multiple segments throughout the day and night.
This is often for no more than 5 – 10 minutes at a time.
For emperor penguins, this averages out to approximately 10.7 hours of sleep a day, although this is subject to change.
Penguins Alter Their Sleep Times
One study took a look at the different arousal stages of an emperor penguin throughout the day, both during the fasting stages and when fed.
The study found that during fasting periods, emperor penguins’ slow-wave sleep increased from 37.5% to 55.4% per day.
This time was taken from wakened hours (not periods of drowsiness or paradoxical sleep).
Other sources claim that during winter hours, when the 24-hour cycle is dominated by darkness, penguins of the extreme south can spend up to 20 hours of the day napping.
Although there are no conclusive studies on exactly how long penguins sleep, mostly due to species differences, it is suggested that the environment plays a large factor in a penguin’s sleep.
Why Do Penguins Sleep for Short Periods?
Like many animals that commonly find themselves hunted, penguins sleep in short bursts as a way to stay vigilant and remain safe.
This type of behavior is common in the animal world and can be seen in mammals, birds, and reptiles of variegating species.
Although polyphasic is the least efficient sleeping method, it is necessary for animals such as penguins, as they are extremely susceptible to prey.
Some researchers believe it is for similar reasons that they huddle and sleep in groups and with their eyes open.
Are Penguins Nocturnal or Diurnal?
Birds differ greatly in their active hours, at night some birds prefer to sleep, while others are their most active.
Although there are subtle differences between species, for example, Antarctic penguins, such as the Emperor Penguin, are mostly diurnal, however, they do perform some activities at night.
African penguins tend to be active during both day and night with irregular patterns. This is known as cathemeral behavior, although they most commonly forage during twilight.
One exception to this is the White-flippered penguin, found only on the small islands on the east coast of New Zealand’s South Island.
These tiny penguins are the only nocturnal penguins.
Although penguins tend to prefer daylight hours, species that live in extreme south destinations, such as the Antarctic, will experience extreme differences in daylight and darkness.
In some cases, the sun will not rise for months, or only come up for a few minutes a day.
Because of this, the sleeping pattern of Antarctic penguins is always changing.
Where Do Penguins Sleep?
Many people relate penguins to cold climates and therefore assume that penguins sleep on ice. Although this is true to a part, it is not the entire story.
Similar to other sea birds, penguins spend a large amount of time in the ocean and therefore are expected to sleep at sea like seagulls.
As penguins spend large amounts of their life at sea, researchers believe that they must sleep, or “nap” while floating on the ocean, however, this has been difficult to observe.
There is also some speculation as to whether they take naps while below the water, but this is not conclusive. Depending on the geographical location, penguins will sleep in different locations.
For example, emperor penguins sleep standing up, while huddling on the ice. African penguins make burrows during the breeding season but are also found sleeping on the beach or among rocks.
