The Oxford Dictionary defines sleep as a recurring condition in which your nervous system shuts down, your muscles relax and your consciousness is suspended for several hours at a time.
It's a popular pastime which even has its own national holiday, although some people still regard those who cherish a late start as unproductive daydreamers...
But it turns out this closed-eyed state of mind not only carries enormous health benefits, it could also do wonders for state wealth across the planet.
New reports show that a lack of sleep is costing the UK economy billions, and is also increasing the risk of death among a growing-number of tired Brits.
The research was conducted by the non-profit research organisation RAND Europe, and is published in a paper titled Why Sleep Matters - The Economic Costs Of Insufficient Sleep.
It found that the impact of sleep deprivation on work rates and personal wellbeing was loosing the UK up to £40 billion a year – around 2% of our overall Gross Domestic Product (GDP).
"Our study shows that the effects from a lack of sleep are massive," lead researcher Dr Marco Hafner told the Press Association.
"Improving individual sleep habits and duration has huge implications"
"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."
From all the countries studied the US maintained the worst financial burden (up to 411 billion dollars or £329 billion) due to insufficient sleep.
It also suffered the most working days lost as a result of sleep deprivation, estimated at 1.2 million.
Japan came in second with losses of up to £110 billion and 600,000 working days, and Germany up to £48 billion and just over 200,000 working days.
Sleeping between seven to nine hours each night is seen as a "healthy daily sleep range" in the report but those who slept less than six hours were 13% more likely to die.
You can find out more on the findings here.