One report even suggests it is leading to mental retardation across the UK.

Rachel Ellison reports: "20% of road accidents are caused by fatigue"

But Professor Jim Horne, a sleep specialist, says the real issue is the impact of sleep loss on things like driving and work, not intelligence.

He is a co-founder of the British Sleep Foundation, which launches on Tuesday. It aims to raise awareness of the dangers posed by a lack of sleep and wants to make napping cool.

It says increased time at work and increased leisure activity means sleep is being squeezed out of people's lives.

Too tired to drive

The foundation's first target is driving while deprived of sleep. It will campaign for people to regard driving while tired as they do driving while drunk.

It will publish a survey to coincide with its launch. Prepared by Gallup, it assesses the scale of sleep-related disorders in the UK.

A preliminary finding was that 11% of those interviewed admitted falling asleep while driving.

The foundation's chairman, Professor Neil Douglas, told the BBC driving is as impaired by sleepiness as it is by drunkenness.

There were three reasons why sleep deprivation was becoming a more important issue in the UK, he said.

Professor Neil Douglas is chairman of the new body

"First, that some people selectively deprive themselves of sleep through social activities.

"Second, work shift patterns - people on rotating shifts and intermittant night shifts are regularly sleep deprived.

"Third, there are a lot of people with sleep disorders that causes them to be sleepy during the daytime."

He said this applied to about one person in 50.

Trendy catnap

The foundation will also campaign for sleep to become "cool".

Professor Horne says that while a cup of coffee can help combat sleepiness the only cure is sleep.

"I would recommend naps. If you're feeling tired, sleep for 10-15 minutes, no longer, and you will feel refreshed."

He said that sleeping longer than 15 minutes takes the body into deep sleep. This means you awake feeling "yucky", he said.

A report in Sunday's Observer says that every hour of sleep lost leads to a drop of one IQ point. Two more points go if another hour is skipped.

This means it is easy for someone with an average IQ to become borderline retarded in the space of a week, the paper says.

Coffee alleviates tiredness, but sleep cures it

But Professor Horne said this research was "nonsense".

"Of course if you're sleepy you will not be at your best," he said. "But you can correct that with a couple of cups of coffee."

He said people underestimated the importance of sleep as the UK moved towards becoming a 24-hour society.

Research published in the New England Journal of Medicine last week linked sleep deprivation with car crashes.

It found that people who suffer from a common sleep disorder are much more likely to have a road accident than other drivers.