How Do Humpback Whales Sleep?

How do Humpback Whales sleep? It is important for whales to sleep but this can be challenging in the marine environment they live in and without a permanent home or bedroom as such to return to each day. Finding the right time to sleep is important and over a 24 hour period of time it is believed that most Humpback Whales will have several phases of sleep either day or night. Sleeping is largely dependant on their environment and what time of the year it is, migration time or feeding time. During the migration season sleep needs to be flexible as thousands of whales are on the migration path and it can be difficult to find a quiet spot to rest in before being interrupted by passing whales. Bays, islands and reef lines can all provide suitable areas outside of the migration rush for whales to relax and sleep. During the feeding season there can be a bit more predictability of when sleep can take place as the whales move with their prey and once bellies are full can spend some time sleeping before getting ready for the next hunt.

The process of how do Humpback Whales sleep is fascinating as they are are voluntary breathers meaning they think about every breath they take. Remaining awake at all times is vital to ensure they remember to take that next breath otherwise they would drown. Incredibly, whales and dolphins have the ability to rest one half of their brain at a time while the other half remains alert and reminds them to take that next breath. Resting in this way avoids the risk of being unaware of predation in the area, vessel strike or other pods encroaching on their space. A whale who forgets to rise to the surface to breath will suffocate and this is why only one half of the brain rests at a time. Sleeping in this way is similar to being in autopilot and generally whales will be motionless at or below the surface, sleeping either vertically or horizontally. Sleeping can also take place when moving slowly and young calves will often sleep while swimming in their mums slipstream.