Sperm whales blow bubbles to help them sleep scientists say

Do you have a bedtime routine? Maybe you like to get snug under the covers, switch off the light and get ready for a good night's sleep.

Sperm whales also have their own way of settling down underwater - but it's a little more unusual.

Scientists have discovered that these huge ocean animals use bubbles to help them sleep while floating in a heads-up vertical position.

Experts say that by doing so, sperm whales are able to control their position and rest peacefully under the ocean's surface, without getting bashed by waves.

Sperm whales are the only whales known to rest in an upright position.

Scientists think this helps them avoid being disturbed by waves at the surface while also saving energy compared with staying deep underwater.

However, until now, experts were unsure how the whales managed to stay in the same spot while they rested.

The new discovery was made by an international team of researchers from the University of St Andrew's in Scotland and the Université de Neuchâtel in Switzerland.

The team used special tags attached to sperm whales, which recorded the animals' movements and sounds as they rested in the sea near the coast of Norway.

They found that the recordings picked up the sound of bubbles being released.

The scientists then used computer simulations to work out how these pockets of gas helped the whales stay in place.

The results showed that by releasing bubbles, it helped the creatures stop themselves from floating back to the surface, allowing them to control their position underwater.

Professor Patrick Miller from the University of St Andrews said that the study revealed a surprising new detail about one of the ocean's more unusual sleepers.

"It is particularly fascinating they are able to make these fine-scale adjustments while they are thought to be asleep," he explained.