Tackling the killer problem of Driver Sleepiness.

This article uses material published in November 2000 by Loughborough University Sleep Research Centre.

The research was carried out by Professor Jim Horne and Dr Louise Reyner. It is quoted here with the authors‘ permission.

Driver sleepiness at a glance

• Driver sleepiness is believed to be a bigger killer on our roads than alcohol
• Driver sleepiness is thought to cause at least 10% of all road accidents and one in five of accidents on motorways and trunk roads
• At least 40 000 serious injuries and nearly 3 500 deaths occurred on roads, according to latest DETR statistics, with drowsiness considered to be a major cause
• Road accidents relating to sleep are also likely to result in death and serious injury as the accidents occur at high speeds when the driver fails to brake beforehand
• Each death on the road costs £1 million (Government statistic) [1999 figures quote £1.6 M]
• Most accidents happen between 2 — 6 am and mid afternoon between 2 — 4 pm, when the body‘s natural clock is set at daily low points
• Falling asleep at the wheel is invariably preceded by feelings of increasing sleepiness that drivers are aware of but often ignore. They will wind down the window, turn up the radio, stretch etc, but drive on
• Neither these latter methods nor the willpower to stay awake have much effect in overcoming sleepiness
• Drivers should plan their journeys with the potential problems of sleepiness in mind
• If they feel tired, drivers should get off the road, find a safe parking place, drink one or two cans of a functional energy drink* and, if possible, take a short nap or doze for no more than 15 minutes. This also gives the drink time to have an effect
• One can of a functional energy drink* is effective in reducing moderate levels of sleepiness (e.g. the 'afternoon dip‘) and sleep related driving impairments for about an hour after being absorbed by the body
• Two cans of a functional energy drink* will almost eliminate this level of sleepiness and sleep related driving impairments for 90 minutes after being absorbed
• Nevertheless, drivers should get adequate sleep, and not see functional energy drinks* as a substitute for sleep
• Men are more at risk of having a sleep related accident because they drive faster, have an overconfident image of their driving skills and are less likely to stop and take a break if they feel tired

*Functional energy — dependent on the addition of caffeine, taurine, glucuronolactone or herbal energy. (Source: Zenith International Retailer Briefing 2000 UK Energy & Sports Drinks). In this research Red Bull was used.

The reasons for the research

Previous research has investigated several known remedies for driver sleepiness, including the popular one of coffee as recommended in The Highway Code. However the problem with this is that there are too many variables in coffee as it can be prepared in many different ways.
The present research centred on functional energy drinks. These contain a combination of the active ingredients listed above. These were chosen because they were commonly used by one of the largest groups involved — young men.

As a result of the research the Sleep Centre recommends:

• Plan your journeys
• If you are feeling tired get off the road
• Drink a can of functional energy drink
• Take a short nap of not more than 15 minutes
• If you cannot take a nap then you should take a break from the road for the same length of time

How the research was done

Groups of 12 volunteers were chosen and carefully screened to fit the requirements of the research. They were tested in a full size car simulator which, by means of a computer, can replicate the usual conditions of motorway driving.

After the first 30 minutes there was a half hour break when the drivers were given identically tasting drinks with neither the driver nor the researcher knowing the identity of the drinks. They came from pre-packed plain bottles containing either the energy drink or an identically tasting control drink.

Separate studies were done using 250 ml and 500 ml quantities using different groups of drivers.

The research findings

The 250 ml group

Half an hour after drinking the energy drink there was a marked decline in the number of driving incidents associated with sleepiness. This improvement lasted up to 90 minutes. Subjective sleepiness was appreciably lower following the drink and lasted for much of the two hour period.

The 500 ml group

Half an hour following the drink the number of driving incidents directly associated with sleepiness was virtually eliminated for 90 minutes and substantially reduced for the remainder of the drive. Subjective sleepiness was significantly lower following the drink and lasted throughout the two hour period.

What does this mean?

The consumption of one 250 ml can of Red Bull significantly reduced sleep related incidents and subjective sleepiness for the first 60 — 90 minutes of driving.

• Two cans (500 ml) practically eliminated sleep related incidents and subjective feelings of sleepiness for the first 90 minutes of driving.
• The results are particularly encouraging against the growing recognition of the problems raised by driver sleepiness. The RAC have highlighted driver sleepiness as a key concern and the DETR have included it in their THINK campaign and followed up by a series of hard hitting adverts.
• Many drivers believe they can easily overcome this sleepiness at the wheel and continue with their journey. Often they succeed but sometimes they don‘t, and instead arrive at another final destination. Even a few seconds doze at the wheel can kill. Opening windows and listening to the radio do not help.
• Driver sleepiness is avoidable. The researches suggest that drivers should keep a couple of cans of a functional energy drink in the glove compartment to be taken during a break from driving. A short nap will also help.
• This advice could save your life and the lives of others.

This summary was written by Keith Bamford following conversation with Dr Reyner. Greater detail is available in a paper entitled "Sleep related vehicle accidents" by J A Horne and L A Reyner published in the BRITISH MEDICAL JOURNAL Vol 310 March 1995.