Lack of sleep is costing the UK economy billions of pounds and putting tired Britons at risk of an early death, according to a report.
Scientists found the effect on sleep deprivation on productivity and health was losing the UK up to £40 billion each year - nearly 2% of the country's Gross Domestic Product (GDP).
Sleeping for just one extra hour a night could add £24 billion to the UK economy, the report suggested.
Lack of sleep could also be putting people at risk of an earlier death. People of any age who slept less than six hours a night on average were 13% more likely to die sooner than those sleeping between seven and nine hours.
Sleeping between seven and nine hours per night was described as a "healthy daily sleep range" in the report, entitled Why Sleep Matters - The Economic Costs Of Insufficient Sleep.
Dr Marco Hafner from RAND Europe and one of the study's authors, said: "Our study shows that the effects from a lack of sleep are massive.
"Sleep deprivation not only influences an individual's health and wellbeing but has a significant impact on a nation's economy, with lower productivity levels and a higher mortality risk among workers."
He added: "Improving individual sleep habits and duration has huge implications, with our research showing that simple changes can make a big difference. For example, if those who sleep under six hours a night increase their sleep to between six and seven hours a night, this could add £24 billion to the UK economy."
The scientists reviewed available research evidence on links between sleep, health, mortality and productivity, collected survey data on sleep duration, and ran computer models to come up with their findings.
But the UK isn't the most bleary-eyed nation. The report found the US felt the biggest financial burden - up to $411 billion (£329 billion) - from lack of sleep while Japan lost up to $110 billion (£88bn).
A poll of 2,000 British adults published earlier this year by the Royal Society for Public Health found that people in the UK slept an average of 6.8 hours.