GIVE YOURSELF A BREAK

You feel warm, your eyelids are heavy, and your perception of hazards left you miles ago, as did your ability to react quickly, so why are you still driving……?

Driving when feeling sleepy causes more deaths and serious injury than drink driving. A safe counter measure to driver sleepiness, especially when a driver has reached the stage of fighting sleep, is to STOP driving, DRINK one or two cups of coffee (containing in total about 150 mg of caffeine) and take a short nap or SLEEP for about 15 minutes.

What are the causes?

Few serious accidents occur in built up areas, as there is plenty for the sleepy driver to see and do. The situation is much worse on long, undemanding and monotonous stretches of roads, such as highways. When we are alert this presents little problem, but if we are driving when we would normally be asleep or when we are fatigued, we face a significantly greater risk of a crash.

Research undertaken for the UK Department of Transport suggests that 1 crash in 10 is due to drivers nodding off – twice the number of accidents caused by speeding. Such crashes are more liable to result in death and serious injury as sleepy drivers do not usually swerve or brake before the impact (1,2).

In New Zealand between 2002 and 2004, driver fatigue was identified as a contributing factor in 134 fatal crashes and 1,703 injury crashes (approximately 11 percent of fatal crashes and six percent of injury crashes each year) and data from Australian road statistics indicate that fatigue accounts for up to 30 percent of single-vehicle crashes in rural areas (3).The figures are similar in an Italian study. (death of the driver in 11.4% of sleep related accidents versus 5.5% in general accidents) (4)

Who does it affect?

Many people use the roads as part of their job so it is not surprising that that many road accidents involve work vehicles. In the UK, the number of fatal road accidents involving lorries is almost double that for cars (5). In the US, the Dept of Transportation considers it likely that every lorry will be involved in at least one sleep related crash during the lifetime of the vehicle (6) and that driver fatigue is a probable factor in 20-40% of truck crashes.

Night work also makes drivers vulnerable e.g. doctors on call or those driving home after night shifts – between 2.00 and 6.00 being the worst period. (7, 8). At around 6.00, drivers are 20 times more likely to fall asleep at the wheel than at around 10.00 (9). Studies suggest that being younger is an important risk factor for sleep related vehicle accidents (about half of the drivers are younger than 30-35 years). Older drivers, and those driving after eating a large lunch, are also vulnerable to sleepiness in mid afternoon. At around 16.00, drivers are three times more likely to fall asleep than at 10.00 or 19.00, the time when our circadian rhythm of sleepiness is least (9).

Starting a long trip on the last workday before a holiday or having to get up unusually early to start a long drive, when there is an increased potential for fatigue, can also put drivers at higher risk of accidents. Holiday driving may be another time of risk. It frequently involves long hours behind the wheel, often in the heat and brightness of the sun and after a less-than-average amount of sleep. In addition such driving is often being undertaken after a long flight to reach our holiday destination - all of which adds up to a potentially deadly combination.

However all of us are very vulnerable to sleepiness if we have had too little or poor quality sleep. Tiredness can easily affect our driving skills and judgements, and if that happens in a built up area, it can be particularly dangerous.

Recognising the danger signals

Driving can be a frustrating and tiring experience at the best of times. Add in busy roads and often stifling heat and your patience can evaporate very quickly and you can also be detracted from those warning signs of tiredness.
Sleep does not occur spontaneously and there is no excuse for falling asleep at the wheel. However, most drivers causing sleep related accidents usually deny having fallen asleep. This is not surprising, as it requires two to four minutes of sleep before any recollection of sleep is possible and most accidents occur when a driver has been asleep for no more than a few seconds (10). However a micro sleep of only four seconds may have potentially fatal consequences; in that time a car driving at 88 kph (55 mph) will cover approx 30 metres (more than 100 feet) – virtually the length of a tennis court.

There are a number of warning signs that drivers should heed as signs of sleepiness:

- Constant yawning
- Tired or sore eyes or going out of focus
- Difficulty in keeping your head up
- Poor lane discipline
- Slow reactions
- Lack of concentration or day dreaming
- Erratic speed
- Difficulty in remembering the last few kilometers or miles

Drivers lullaby

Singing or listening to music to keep alert and counteract tiredness is sadly one of the popular myths. Such action provides only a short-term benefit and may be a distraction for drivers from being so aware of their sleepiness and poor driving. Similarly the benefits of cold air on the face, is also a myth (11). Such measures are often taken when a driver has reached the stage of fighting off sleep. At this point the safe thing to do is to stop driving as soon as possible, take a break for at least 30 minutes, drink a couple of cups of caffeinated coffee and take a brief nap.(17)

How coffee can help

Much research has been undertaken to ascertain the most feasible method of alleviating sleepiness among drivers. Some laboratory studies show that relatively low amounts of caffeine, 100-200mg, significantly improved alertness in sleepy subjects (12, 13, 14)

Other laboratory studies (15,16) have involved comparing a number of factors considered to make a difference. They include different periods of rest at a driving break, varying levels of caffeine intake and working with subject at different periods of the day, and varying the amount of sleep deprivation.

Both caffeine and being allowed to nap, significantly reduced major and minor driving incidents, and had a powerful effect in suppressing sleepiness and signs of drowsiness. The most effective combination was, during a 30-minute break, to drink one or two cups of coffee, which provides about 150 mg of caffeine and then nap for about 15 minutes. (17)

Mind how you go

Drowsy driving is not illegal but it is just as, if not more, dangerous than drink driving. If you feel sleepy while driving this means you are more likely to crash. Stop, give yourself a break, and make this your wake up call to safer driving!

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