Do Sharks Sleep?

Whether sharks sleep or not? This question has been a topic of discussion for a long time because it is quite difficult to explain what actually ‘sleep’ meant to a shark. While taking this topic under discussion, another question comes into the focus of attention that when do sharks sleep during day or night? Do they fall asleep when they are tired or what? To answer such a question let’s go through the information gathered in this article.

Do Sharks Sleep?

The answer to this question is “YES” sharks sleep but they keep their eyes open when they are sleeping. The sleeping pattern of sharks is different from other animals due to the reason that sharks must keep themselves in a state of motion for their survival.Sharks usually lack a swim bladder, so whenever they stop swimming they may sink.

However, the large oil filled liver of the sharks provides them buoyancy, which prevents them from sinking and helps them to float. Moreover, sharks are also dependent on the movement of pectoral and caudal fins which also helps them to float. So whenever sharks stop swimming or undergo a resting period they settle themselves down at the bottom of the oceans.

How do Sharks Sleep?

As we have understood sharks do sleep but it is more like a restful period as compared to a deep sleep like other animals. Sharks adopt various sleep mechanisms – let’s see what mechanisms do they adapt to sleep!

1: Sleeping with the Help of Spiracles

With the help of spiracles, sharks can easily rest on the ocean floor because the spiracles help to push water in and ventilate the gills, so that sharks can sleep without being in a state of worry about swimming or breathing. Moreover, research showed that whenever sharks fall asleep they are somewhat in their senses and are fully aware of their prey or threatening potentials that might enter their locality.

2: Sleeping Swimming Mechanism

Some shark species rest on the floor of the ocean more than being active and swims in water, this resting phase is named as sleep swimming. In these conditions, sharks are not completely unconscious; rather some parts of  their brain fall asleep. But various studies showed that it’s not a brain, it is the spinal cord that helps sharks to swim freely. Thus, sharks may fall asleep even when they are swimming or floating.

3: Sleeping with Yo-Yo Swimming Mechanism

The other way by which sharks sleep is named as “yo-yo swimming”.  This type of sleeping pattern is mostly used when the sharks had to swim long distances. In this sleeping pattern sharks swim towards the upper surface of oceans and then slither back down. This sleeping pattern thus helps them to rest when they are tired of travelling long distances.

When do Sharks Sleep?

The sleeping pattern of the sharks is completely based on their Circadian Rhythm. This is because sharks mostly sleep when their instincts give them a signal to do so. Sharks do not show any strict predilections for being diurnal (during day time) or nocturnal (during night time). According to various reports, sharks have very less time period of sleeping with respect to their active period. So sometimes, it’s actually very hard to understand how sharks sleep or take rest when they need to!


Sharks like other animals do not undergo deep sleeping patterns but they do have some restful sleep while they are swimming or resting at the bottom of the ocean. Sharks adopt different patterns of sleeping, either with the help of spicules, sleep swimming or yo-yo swimming to fall asleep. Hope the information gathered above may provide enough knowledge about the sleeping of sharks. Or if you want to check out if they really sleep or not, why don’t you take a swim with sharks?