Scientists have developed a blood test that could help police identify suspected drowsy drivers in road traffic accidents or help employers assess an employee’s fitness to drive.

The test can identify whether somebody has skipped a night’s sleep. The study at the Sleep Research Centre at the University of Surrey, led by Professor Derk-Jan Dijk, involved 36 participants who had skipped one night of sleep.

During this 40-hour period of sleep deprivation, blood samples were taken and changes in the expression levels of thousands of genes were measured.

A machine-learning algorithm identified a subset of 68 genes and with 92% accuracy could detect whether a sample was from a sleep-deprived or well-rested individual.

This breakthrough paves the way for a future test which will be able to assess if a driver was sleep deprived.

Previous research in this area has shown that drivers who get just one to two hours less than the recommended daily allowance in a 24-hour period nearly double their risk for a car crash.

Dr Emma Laing, senior lecturer in bioinformatics at the University of Surrey, said: “We all know that insufficient sleep poses a significant risk to our physical and mental health, particularly over a period of time. However, it is difficult to independently assess how much sleep a person has had, making it difficult for the police to know if drivers were fit to drive, or for employers to know if staff are fit for work.”

“Identifying these biomarkers is the first step to developing a test which can accurately calculate how much sleep an individual has had,” added Simon Archer, professor of molecular biology of sleep at the University of Surrey.

“The very existence of such biomarkers in the blood after only a period of 24-hour wakefulness shows the physiological impact a lack of sleep can have on our body.”

Professor Derk-Jan Dijk, director Surrey Sleep Research Centre at the University of Surrey, said: “This is a test for acute total sleep loss; the next step is to identify biomarkers for chronic insufficient sleep, which we know to be associated with adverse health outcomes.”

Chris McClellan, CEO of Ram Tracking, welcomed the development. He said: "The fast-moving dynamics of working life mean that employers especially have a duty of care to ensure that where possible, their drivers are alert and fully able to carry out their duties.

“While vehicle tracking devices allow for the monitoring of driver whereabouts and provides the ability to react quickly if someone has an accident, tests that ensure drivers are alert enough to be on the road can only be a good thing, by both addressing the risk of tired motorists at source, and encouraging more awareness of the issue as a result."