A CEO has found a clever way to encourage his employees to sleep more - by paying them.

Mark Bertolini, the head of US health insurance company Aetna, has started to pay employees who regularly get seven or more hours of sleep a night.

"If they can prove that they get 20 nights of sleep for seven hours or more in a row, we will give them $25 (£17.52) a night, up to $500 (£350.45) a year,", Mr Bertolini told CNBC’s Squawk Box.

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Employees taking part in the programme use Fitbit fitness trackers to monitor their sleeping patterns.

The Aetna CEO said he believes there is a direct link between sleep, employee productivity and company profits.

He bought in researchers from Duke University, who found employee productivity increased by 69 extra minutes per month as a result of the company investing in wellness and mindfulness programmes.

Appearing alongside Mr Bertolini on CNBC's Squawk Box, Arianna Huffington, co-founder and editor-in-chief of the Huffington Post, said: "It really changes the cultural delusion that most businesses have been operating under, which has been ... the more exhausted and burned out the employees are, the more productive they are."

Adults in the UK are sleeping an hour less than they should each night, a recent study found.

According to the Royal Society for Public Health, lack of sleep causes a third of people to feel depressed and more than half to get stressed.