Dr Neil Stanley Independent Sleep Expert
© Dr. Neil Stanley 2013-2019
Sleep and driving It has been estimated that sleepy drivers in fact now kill more people on Europe’s roads than drunk drivers with sleepiness thought to be involved in 16–60% of road accidents. Most people are aware of the hazards of drinking and driving. But driving whilst sleepy can be just as dangerous because even moderate sleep deprivation affects driving performance as much as low-levels of alcohol. Your performance after being awake for 16 hours is as bad as if you were over the drink driving limit. Both alcohol and a lack of sleep inhibit your ability to react quickly e.g. to a suddenly braking car. They also affect your judgement e.g. misjudging the width of your car or the sharpness of a bend. Falling asleep at the wheel is particularly dangerous as it only takes a matter of seconds for your car to come off the road. And because you are asleep you do not take any evasive action and so you hit what you hit, hard. That is the way the police can tell if the driver has fallen asleep at the wheel, no skid marks. There can be any number of underlying causes of sleepy driving. These include o not getting enough sleep o having interrupted or fragmented sleep o having a chronic sleep debt o working shifts o undiagnosed or untreated sleep disorders or other illnesses that can disrupt sleep such as pain, depression, etc. o time awake before driving o the use of sedating medications o the consumption of alcohol o Early morning starts to beat the traffic o Overnight drives when it is quieter on the road Any combination of these factors can greatly increase one's risk for a sleep-related accident. The most vulnerable time for sleep related car accidents is around 2–7am thus you should, if at all possible, avoid driving during these times. There is another, smaller, peak of accidents in the mid-afternoon. Things to be aware of as warning signs that you are too sleepy to drive safely include: o trouble keeping your eyes focused o yawning o drifting across the lane markers o being unable to recall driving the last few miles o at night fixating on and driving towards lights on the road If you experience any of these or just feel sleepy while driving, pull off the road and take a nap for 15–20 minutes. Try and schedule frequent breaks on long trips, your car may be able to drive 500 miles on a tank of petrol, but you shouldn’t. Take a short break every couple of hours or so. Don’t count on caffeine to keep you awake and alert. Caffeine can take up to 30 minutes to ‘kick in’ and it only provides a short term boost to alertness, so it cannot overcome excessive sleepiness or relieve a sleep debt. Also the amount of caffeine in any particular cup of coffee can varies widely and so you may not actually be getting any boost from the coffee, but because you think you have you will carry on driving even though you are still as sleepy.  The sleepier you are the less able you are to accurately judge your level of sleepiness. In some people excessive caffeine consumption has actually be shown to cause sedation. Opening the window or turning up the radio won’t help you stay awake while driving. If you work shifts, particularly night shifts the try, if possible to use public transport. And finally never combine alcohol with driving, but especially when you are sleepy as one beer when you are sleep deprived will affect your performance as much as two or three beers when you are well rested.