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Is drowsy driving as dangerous as we think?


We’re all steering away from drunk driving because we know what the implications of it are and it’s just not worth it. But no one seems to have the same thought when they get behind the wheel after only having 4 hours of sleep.

The incidence of drowsy driving accidents is often worse than those of drunk driving. And they’re a lot more prevalent than we think.

Drowsy driving isn’t an isolated problem

Although we’d like to think that drowsy driving applies only to truck drivers or those who work night shifts, it doesn’t. According to Matthew Walker, author of Why We Sleep, two-thirds of the world isn’t getting the recommended 8 hours of sleep nightly. Now that may not seem all that bad when you feel fine after less than 8 hours of sleep. But according to Harvard Medical School, it’s hard to recognise when you’re drowsy the more your sleep debt accumulates. When we’re under sleep deprivation’s umbrella, we can’t recall what it’s like to be fully rested. And if you’re like us, reading this may have you thinking, “Yeah but that’s not me”.

And it may not be, but it still isn’t isolated. Despite people struggling to notice when they are sleep deprived, a poll done by the National Sleep Foundation found that 60% of drivers admitted that they knowingly get behind the wheel when feeling drowsy. Additionally, over one-third of all drivers start to doze off, of which 13% say that they have done so at least once a month.

According to Matthew Walkera>, 1.2 million car crashes every year are attributed to drowsy driving in the United States. Those are frightening numbers and when you think that it’s hard for one to even detect sleep deprivation in themselves, drowsy driving becomes a bit more real. But what is drowsy driving exactly?

Drowsy driving explained

Drowsy driving is also known as tired driving or fatigued driving. It is a combination of driving and sleepiness. This can occur when a person has not had enough sleep. And in addition to being sleep deprived, this person has taken medication that has a sleepy effect, and or drank alcohol. As a result, the driver’s reaction time may be dangerously slow or impaired completely.

It’s possible to be asleep and awake at the same time

If you look at the actions of drowsy driving and drunk driving, they both make it hard to pay attention to what’s in front of you. But the difference here is that drunk driving means you react slower whereas drowsy driving puts you into a microsleep. You know those moments when you’re nodding off and gravity starts to play games with your head? You find yourself jolting out of that few-second snooze looking around you to see if anyone noticed. That’s microsleep, well at least the non-scientific description.

Discover magazine puts it quite nicely: “This weird state of consciousness is characterised by brief bursts of sleep that happen while a person is awake — often while their eyes are open and they’re either sitting upright or even performing a task. During microsleep, parts of the brain go offline for a few seconds while the rest of the brain stays awake. And usually, people don’t realise it’s happening to them.”

Microsleeps allow for zero reaction time, so by the time you’ve woken up, it’s too late to brake or swerve out of the way of something. And what’s even more alarming is that microsleeps can happen at any time, even when you’re transferring pocket money to your daughter. It’s possible to whack on an extra zero before you realise what you’re doing (whoops).

To put microsleeps into context and to show you just how easily they could happen, you have to look at how much sleep you’re getting. You could be severely sleep deprived or you could think you’re getting a fair amount of shut-eye but it’s just not enough. How so? Let’s say you have an all-nighter — binge-watching cake videos on Instagram or working through the night to meet a deadline, doing that can increase your chance of microsleep by 400%. Not by 4%. Not 40%. Not even 40% x 4. But by 400%. It’s the same if you go 6 nights with 4 hours of sleep and 10 nights with 6 hours of sleep.

Not only are microsleeps something to be wary of but there’s also the notion that being sleep-deprived can make one behave in the same manner as being over the legal drinking limit.

(HOLD THE BRAKES) Yes, you read that correctly. Research indicates that after being awake for 17-19 hours, people’s performance is equivalent to that of having a blood-alcohol level of 0.05%. In most countries, that’s the legal drinking limit. If you stay awake for longer, say around 20 hours, your equivalent blood-alcohol level reaches 0.1%. This statement may raise a few eyebrows, which leads us to our next point.

Is it apples vs apples? Or apples vs oranges?

So not getting enough sleep could result in your actions being similar to that of being over the legal drinking limit? But how can you express sleepiness in terms of drunkenness? Surely you’re comparing apples to oranges and not apples to apples?

The research mentioned above explains the results of an experiment in which 39 participants were required to perform several tasks. Each person had to engage in tasks when under the influence of progressively intense alcohol inebriation and then again on another day under progressively intense sleep deprivation. The interesting thing is that they didn’t use the driving ability to make the comparison — they used a series of focused tests to pick up the extent of deterioration of various brain functions and motor skills (things like testing reaction times, hand-eye coordination, memory, etc.).

The fact that the experiment was conducted with a rather small number of people shouldn’t be ignored. Certain people are likely to react very differently to sleep deprivation and/or alcohol consumption which makes a direct 1-to-1 comparison between the two impossible.

But the results of the experiment still act as useful rules of thumb, bringing drowsy driving into the more familiar context of drunk driving for which our intuitions around what is and is not acceptable tend to be a little more sharpened.

How can you prove an accident occurred because of a drowsy driver?

As much evidence as there is that drowsy driving is prevalent and happening — it’s hard to attribute it as the cause of an accident. There’s no breathalyser equivalent for picking up poor sleep.

However, some markers can help classify the crash. Things like there being no sign of skid marks or evidence of evasive manoeuvres — recall the microsleep point from above that drowsy driving accidents are the result of drivers not reacting at all due to being asleep at the time of impact. Another marker is that the driver is alone — you’re less likely to feel drowsy if you have a tone-deaf passenger who sings along to what’s on the radio.

Additionally, one can take the strenuous task of looking at police-reported accident data to try and gauge the extent of the problem. But it’s proven a struggle to find reporting consistency both between and within countries. For example, in America, some districts have police with little to no training in how to look for signs of drowsy driving. In other districts, there isn’t even an option to attribute an accident to drowsy driving on the data system.

So it seems like reliable empirical data on how many accidents can be attributable to drowsy driving simply doesn’t exist. Getting a feel for the prevalence of drowsy driving accidents therefore requires some theoretical work.

Using somewhat more reliable statistics on the sleeping habits of a population in conjunction with controlled experimentation into the effect different levels of sleep deprivation have on driving ability, we can extrapolate from the experiments to the greater population. Sources tend to put the best estimate of the actual number of drowsy driving accidents at between 10-30% of all crashes.

So the next question might be, is it illegal to drive while sleep deprived?

Even though it’s not as clear-cut as it should be, legislation is currently being crafted in a few US states due to the number of accidents that occur from drowsy driving. In Arkansas, when a driver is involved in a fatal accident and has gone for 24 hours without sleep, it is a punishable offence under negligent homicide. This goes to show that drowsy driving is being recognised as a serious and dangerous issue.

In other US states, physicians are required to waive their doctor-patient confidentiality in the interest of drowsy driving detection — if they believe that their patient’s sleeping habits/condition puts themselves and others at risk while they drive, they must report to the relevant authority. “If the highest-risk patient (eg, severe daytime sleepiness and a previous motor vehicle crash or near miss) insists on driving before the condition has been successfully treated or fails to comply with treatment requirements"—An expert panel of the American Thoracic Society.

But requiring physicians to report on their patients presents its own problems. It could be argued that the main result of this requirement is that fewer people with poor sleep hygiene will seek out medical help.

Even though we made mention of drowsy driving not being isolated to truck drivers, there are laws around work hours for truck drivers that have been put into place in numerous countries. They do tend to be those at the highest risk of causing a drowsy driving accident and are often not in the financial position to refuse unreasonable work hours from their employers — so it makes sense to give this group of people some extra attention and impose a simple limit on the number of hours that may be worked in a given week.

Beyond initiatives like this, it’s difficult to make drowsy driving illegal. This is mainly due to the lack of a “sleepiness breathalyzer”. Either way, difficulties with implementation should not take away from the seriousness of the situation. If and/or when a fatigue detection device is developed, it’ll be interesting to see how many countries will try to bring in laws comparable to drunk driving laws.

In the interim, there is a case to be made for more public education on sleep and the impact of sleep loss on driving. Probably the scariest fact about drowsy driving that we’ve learnt is the fact that most of the time, we don’t even know that we’re too sleepy to drive safely.

Being cognizant of this flaw will at least get people to think twice about getting behind the wheel after an all-nighter at work.


The good news is that the government doesn’t have to solve this problem on their own — it seems private companies are starting to cotton on to the fact that the sleep of their employees should be prioritised.

“Work smarter, harder and longer.” A phrase known all too well amongst professionals, but the latter part of that phrase is factually contradictory to the two previous words. Even Silicon Valley is slowly starting to realise this.

Arianna Huffington, an Uber board member says, “Uber is a data-driven company, and the data shows unequivocally that when you work longer, you are not working smarter. When you’re always on you’re depleted, you are distracted.”

Uber recognised that drowsy driving is an issue for all who are on the road. In their efforts to prevent it, they implemented a feature that requires all drivers to go offline for six hours straight after 12 hours of driving. The feature counts how many hours are spent driving— drivers receive periodic notifications pointing out that they are approaching the 12-hour limit. Once they reach 12 hours, the drivers will automatically go offline and must rest for 6 hours. Only after the 6 hours have lapsed, will they be able to start receiving trip requests.

Similarly, consulting firm McKinsey & Co. are realising that sleep deprivation is often neglected by organisations, including them. So much so that they have started implementing company policies regarding sleep hygiene and the like in the hope that it helps their bottom line. “It’s time for organizations to find ways of countering the employee churn, lost productivity, and increased healthcare costs resulting from insufficient sleep.”

The onus isn’t solely on other parties to prevent drowsy driving, it also comes down to the individual who gets behind the wheel. So what do you do when you hear the hum of the rumble strip you’re not meant to be driving over?

“There are many things that I hope readers take away from this book. This is one of the most important: if you are drowsy while driving, please, please stop. It is lethal.” - Matthew Walker

If you must keep driving, cold air to the face (opening a window or blasting the aircon) might be a temporary solution. But there’s limited evidence of this, it’s best to look at it as a way to buy yourself 15 minutes while you find a place to stop. An interesting note is that the common suggestion of listening to the radio to help with sleepiness might actually backfire — there’s reason to believe that listening to the radio increases your risk, and the leading theory is that the radio distracts the driver from the extent of their sleepiness.

Once you’ve stopped, the best thing that you can do is take a nap. Just 15 minutes has been shown to improve driving performance significantly for over an hour. Alternatively (or in addition to) caffeine may be an option and has been shown to have a similar short-term effect to napping. But note that caffeine typically takes around 30 minutes to take effect, so once you’ve stopped and had a coffee, relax (or nap) for 30 minutes before heading onto the road again.

Another area that you could focus on is practising good sleep hygiene. First, it’s worth noting that each night isn’t a chance to wipe the sleep slate clean. Many consecutive nights of semi-bad sleep can be equivalent to one night of really bad sleep. But rather than focus on what could go wrong, look at what could go right with just one step in the right direction.

We know that lots of advice given may be overwhelming as well as difficult to implement, so we’ve compiled some tips that our Naked team members have used and found valuable in improving their sleep routine and quality of sleep overall.

If you nap, nap smart. Napping too much, or too close to bedtime reduces your sleepiness enough that it’s not strong enough to get you to nod off. So, don’t take naps after 3 pm, and try and keep the naps that you do take down to between 20-30 minutes.

Be cool. Your body temperature needs to drop for you to fall asleep. It does this on its own, but it helps to nudge it in the right direction. So a good way to help along the process is to use the nighttime ritual that’s been around in several cultures for thousands of years: washing your hands and face before bed.

Stick to a sleep schedule.

We should aim to go to bed and wake up at the same time each day. Unfortunately sleeping late on weekends doesn’t make up for poor sleep during the week.

Get the right sunlight exposure. Sun exposure during the day helps us to regulate sleeping patterns. Try to get outside in the natural sunlight for at least 30 minutes per day.

Don’t stay in bed if you (really) can’t sleep. If you find yourself still in bed for more than 20 minutes, or you’re starting to get anxious in bed, get up and do something else until you feel sleepy. Anxiety whilst trying to sleep can make it harder to fall asleep.

There are a lot of positives to getting that much-needed shut-eye each day — we promise. It makes us more productive, happier and of course, we have to mention, healthier. It helps us concentrate, improves memory, reduces stress, builds immunity and of course reduces your risk of falling asleep at the wheel. Do you know when your phone is fully charged? Imagine we knew what that felt like.


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