Have you ever wondered how sleep, or more precisely, a lack of sleep, can affect your driving?

We have, which is why we decided to test how different levels of sleep can impact on your driving abilities. Watch our video below to see how a set of triplets from Essex performed on a 90 minute simulated drive with a full night’s sleep, interrupted sleep, and no sleep. Keep scrolling for more information on the research, including our findings and comments from the people involved.

Sleepy Drivers Experiment

Scroll to see the facts

We took a set of triplets and undertook an experiment to discover how serious it is to drive whilst tired, and how lack of sleep can affect driving ability. Pat, Rob and Steve, aged 27 from Essex, took part in the experiment which saw each of them have varying levels of sleep.

After drawing straws, Rob was chosen to get a full night’s sleep (7-8 hours), Steve had disrupted sleep via a simulator baby and poor Pat picked the shortest which meant he had no sleep whatsoever.

The next day each triplet took the same test at TRL, which provides independent research, consultancy, testing and certification for transport. This involved staying in the same lane for 90 minutes at 60 miles an hour. During the test each triplet had to flash his lights every time a red light appeared to monitor reaction time, and each wore a heart rate monitor to track fatigue levels.

The results were shocking and demonstrated just how badly sleep deprivation can affect driving.

The Results

Fatigue Alerts Chart Lane Departure Frequency Chart

What they said

“The findings of our experiment reveal just how important it is to only undertake driving when feeling alert and having had sufficient sleep. The key finding here was how affected Steven was with disrupted sleep as this is most common to real life.”

“One dangerous aspect of fatigue is how it can come and go quite suddenly. You can get a false impression that you’ve overcome it, only to find that it strikes again a short time later when you perhaps aren’t expecting it.”

Simon Tong, principal psychologist at TRL

“For me, the results show how important having a good night's sleep is if you're about to do a long drive.”

Robert Davis

“I found the drive really difficult. I was really tired and towards the end I drifted between all three lanes. It brings it quite close to home knowing that if you've got a little boy or girl it's dangerous having broken sleep.”

Steven Davis

“It was very tough. After 30 hours of not sleeping, as it went on it got harder and harder and I just found myself nodding off. The results for me were what I expected - having had no sleep at all, I knew the results would be bad, but the broken sleep results shocked me.”

Patrick Davis


  • Who?

    The research was performed on Patrick, Robert and Steven Davis, a set of triplets aged 27 from Essex. We chose triplets to ensure the experiment was as fair as possible due to their genetics and upbringing making them most likely to look and think alike.

  • Where?

    Transport Research Laboratory (TRL), a provider of independent and impartial research, consultancy, testing and certification for all aspects of transport.

  • Why?

    As an online bed retailer we know how important a good night's sleep is. With one in five car accidents put down to fatigue, and the fact that there are no legal laws around driving when tired (unlike when drinking), we wanted to raise awareness of how dangerous driving when tired can be.

  • How was the research analysed?

    Simon Tong, Principal Research Analyst at TRL, observed each drive, monitoring a range of factors including fatigue alerts, lane departure frequencies, reaction times and speed.

  • What are fatigue alerts?

    Whilst undertaking the experiment, each triplet drove whilst wearing a heart rate monitor which gave alerts when their heart rate dropped to a level classed as fatigued.

  • What does lane departure frequency mean?

    The experiment asked them to stay in one lane for the whole duration of the drive, and measured how many times they departed from that lane, as well as how many seconds they were out of the lane for in total.