There are many ways in which a lack of sufficient sleep will kill you. Some take time; others are far more immediate.

One brain function that buckles under even the smallest dose of sleep deprivation is concentration. The deadly societal consequences of these concentration failures play out most obviously and fatally in the form of drowsy driving.

Every hour, someone dies in a traffic accident in the UK due to a fatigue-related error. There are two main culprits of drowsy-driving accidents.

The first is people completely falling asleep at the wheel. This happens infrequently, however, and usually requires an individual to be acutely sleep-deprived (having gone without shut-eye for twenty-plus hours).

The second, more common cause is a momentary lapse in concentration, called a microsleep. These last for just a few seconds, during which time the eyelid will either partially or fully close. They are usually suffered by individuals who are chronically sleep restricted, defined as getting less than seven hours of sleep a night on a routine basis.

During a microsleep, your brain becomes blind to the outside world for a brief moment, and not just the visual domain, but in all channels of perception. Most of the time you have no awareness of the event.

More problematic is that your decisive control of motor actions, such as those necessary for operating a steering wheel or a brake pedal, will momentarily cease.

As a result, you don’t need to fall asleep for ten to fifteen seconds to die while driving. Two seconds will do it. A two-second microsleep at 30 mph with a modest angle of drift can result in your vehicle transitioning entirely from one lane to the next.

This includes into oncoming traffic. Should this happen at 60 mph, it may be the last microsleep you ever had.

Next time you sleep deprived think not once, not twice but 3 times before you get behind the wheel of your car.


Driving a car when sleep deprived is the equivalent of someone at a bar who has had far too many drinks picking up his car keys and confidently telling you, “I’m fine to drive home."

Drunk driving and drowsy driving are deadly propositions in their own right, but what happens when someone combines them?

It is a relevant question, since most individuals are driving drunk in the early-morning hours rather than in the middle of the day, meaning that most drunk drivers are also sleep-deprived.

We can now monitor driver error in a realistic but safe way using driving simulators. With such a virtual machine, a group of researchers examined the number of complete off-road deviations in participants placed under four different experimental conditions:

(1) eight hours of sleep (2) four hours of sleep (3) eight hours of sleep plus alcohol to the point of being legally drunk (4) four hours of sleep plus alcohol to the point of being legally drunk.

Those in the eight-hour sleep group had few, if any, off-road errors. Those in the four-hour sleep condition (the second group) had six times more off-road deviations than the sober, well-rested individuals. The same degree of driving impairment was true of the third group, who had eight hours of sleep but were legally drunk.

Driving drunk or driving drowsy were both dangerous, and equally dangerous.

A reasonable expectation was that performance in the fourth group of participants would reflect the additive impact of these two groups: four hours of sleep plus the effect of alcohol (i.e., twelve times more off-road deviations).

After thirty years of intensive research, scientists can now answer many questions.

The recycle rate of a human being is around sixteen hours. After sixteen hours of being awake, the brain begins to fail.

Humans need more than seven hours of sleep each night to maintain cognitive performance. After ten days of just seven hours of sleep, the brain is as dysfunctional as it would be after going without sleep for twenty-four hours.

Three full nights of recovery sleep (i.e., more nights than a weekend) are insufficient to restore performance back to normal levels after a week of short sleeping. Finally, the human mind cannot accurately sense how sleep-deprived it is when sleep-deprived.

As a result, 1.2 million accidents are caused by sleepiness each year.

Hope the above gets you thinking!

#sleep #whywesleep #matthewwalker

Coach HB

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