About one in six British HGV drivers suffers from a form of a sleep disorder requiring medical help, a study says.
A lorry driver said to have the condition was jailed for a fatal crash
If left untreated, obstructive sleep apnoea could lead to potentially fatal road accidents, according to experts.
Sufferers can experience obstructions of their airway during sleep, resulting in "fragmented" rest and excessive daytime drowsiness, they say.
The Respironics study, to be featured on BBC1's Real Story, looked at more than 900 drivers in England and Wales.
It was led by sleep scientist Melanie Marshall who said sufferers "are more lethal than drink drivers".
But the Road Haulage Association denied the problem was rife among HGV drivers in the UK.
Obstructive sleep apnoea, or OSA, is present in 1-4% of the population, mostly among middle-aged men, says the Royal College of Physicians.
During sleep, the airway from the mouth to the lungs collapses either completely or partially, causing oxygen to be lost from the blood, which in turn creates "micro arousals".
"Sufferers are not physically aware of their awakenings," explained Ms Marshall, "but they can have hundreds of these over a period which leads to fragmented sleep."
The findings of her research for Respironics could have serious implications for both the NHS and the road haulage industry.
Crashes caused by drivers falling asleep at the wheel account for around one-fifth of accidents on Britain's motorways.
In January 2002, lorry driver Paul Couldridge was jailed for eight years and banned from driving for life after killing an engaged couple in a pile-up on the M20 in Kent.
Maidstone Crown Court heard Couldridge had already been told by doctors to stop driving because he was suspected to be suffering from OSA.
He ploughed into a BMW on the opposite carriageway, having fallen asleep.
He had nodded off in the cab of his vehicle 15 times on previous journeys, it emerged, causing minor accidents.
All drivers who were studied by Respironics were kept anonymous. Those who tested positive for OSA were given immediate treatment.
The results were studied by an independent monitoring panel drawn from UK medical and clinical posts and other professions.
The study statistics were prepared by the London School of Hygiene and Tropical Medicine.
One in three participants were shown to have some form of OSA, with about one in six suffering from such a severe form of the illness that they needed treatment.
So, with an estimated 500,000 HGV drivers on Britain's roads, if the pattern was repeated across the UK, about 80,000 could need help.
Sleep scientist Melanie Marshall led a two-year study of HGV drivers
"I think the study actually highlights how much of a problem it is," says Professor John Stradling, a world expert in sleep disorders.
"Unknowingly, they have this medical disorder which they have the right to be screened for or diagnosed with and treated, to actually make our roads safer."
Real Story reveals that some truckers who suspect they may have the condition are too frightened to come forward - because once a diagnosis is given, their HGV licence is suspended until they have been treated.
In this time, they risk losing their job.
In many parts of the country there are long waiting lists for treatment, while in others it is not funded, despite the necessary machine costing no more than £300.
However, the Department of Health told the programme: "Patients with sleep apnoea are able to access a range of NHS and social care services, tailored to meet their individual needs.
"It's for health professionals in primary care organisations to determine the appropriate level of provision."
The Road Haulage Association said "it would be irresponsible to claim that this problem is especially rife within the UK road haulage industry".
They added that before anyone could train to become a commercial driver they were required to pass a rigorous medical examination. However, Real Story found that this did not include a test for OSA.
The Transport and General Workers' Union said it urged the government "to bring about legislation in regard to compulsory testing of sleep apnoea."
The Department of Transport said it was looking at the new findings on obstructive sleep apnoea.
But the DVLA reminded all drivers it was their responsibility to tell them if they suspected they had the condition.
Real Story: Killer in the Cab - BBC One, Monday 21 November, 1930 GMT.