The dangers of having a microsleep

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Most people view a good night’s sleep as a long period of unconsciousness.

However if you visit a Sleep Laboratory on a Saturday night, the researchers there will be hard at work to prove this simple notion wrong.

The Professor of Psychiatry at the Flinders University of South Australia, Leon Lack, says the truth of a decent night’s sleep is more like a hair-raising show ride.

Professor Lack is at the forefront of pioneering research into sleep and all its vagaries.

He’s responsible for the Sleep Research Laboratory at Flinders University where willing participants get wired up and tucked into bed for the night while others watch, monitor and learn.

Basic research into sleep is a relatively new field and Professor Lack and his colleagues have learnt a lot.

“Normal sleep for a 20 year old adult is more like a roller coaster ride, a bit like the mad mouse,” Professor Lack says.

“Every hour or so you progress into a deeper sleep where you come into a 40 to 50 minute period of deep sleep before coming back up to a lighter and lighter sleep until you hit REM (Rapid Eye Movement) sleep. And then you go back down again into another deep sleep but shorter than the first one before coming back up into REM where you stay for a bit longer again. Each cycle into deep sleep and back into REM lasts about 90 minutes."

“If you wake someone during the REM phase they will often recreate vivid and amazing dreams. This is where eyelids flicker back and forth, breathing might become irregular, fingers might twitch, while most of the body is perfectly and deeply still. You can wake from REM feeling very alert, even agitated.”

Sabre tooth tigers

Professor Lack believes that REM sleep is a biologically developed mechanism to check for sabre tooth tigers in the night – the flight or fight response.

So, every 90 minutes or so we do actually wake up and he says this is perfectly normal and healthy.

Most of the time, we don’t remember waking, unless we are insomniacs or stressed about something and then we can have trouble going back to sleep.

For many people, the reassurance that waking is a normal part of sleep can be enough to cure their insomnia. It’s the panicking about being awake, says Professor Lack, that ups the flight or fight response and makes it even harder to get back to sleep.

Party on

The Sleep Laboratory has unearthed another interesting phenomenon, and it’s particularly relevant for young drivers.

Professor Lack noticed that student participants in the laboratory were falling asleep very quickly and much faster than the older participants. He was intrigued.

Participants are a long way from their own comfy bed and have monitors on fingers and around their heads – not that conducive to falling asleep easily.

He even asked one young woman to forget the sleep study they were doing and try and stay awake. She managed another two minutes before nodding off – five minutes after lights out. And no, she wasn’t just a sleepy head, in fact she reported rarely feeling sleepy and never falling asleep during the day.

Further studies have indicated that while young people might not feel particularly sleepy and could even play a high energy sport if you asked them, given a chair or bed, they will fall asleep very easily.

The good news is that being young means sleep deprivation probably won’t stop you having fun. Out partying all night? Game of soccer in the arvo? No worries.

But what about driving a car?

Professor Lack says the most frightening scenario for anyone, but particularly a young driver, is sleep deprivation coupled with that long stretch of boring road.

This is when we are most at risk of having a microsleep – a short period of unconsciousness which is actually a first stage of sleep or light sleep. The one we’ll have no memory of and completely deny even happened if we’re woken from it.

“Someone could be clinically asleep, in a light sleep, and you could ask them ‘Are you asleep?’ and they’ll answer you ‘No, I’m awake’ but if you ask them to tell you what was just on the radio or TV in the background, they won’t be able to tell you,” says Professor Lack.

Not a problem if you’ve just missed a couple of minutes of your favourite TV show. Tragic and possibly fatal if you’re behind the wheel of a car.

Professor Lack stresses that being aware of feeling sleepy is vital when you’re on the road. But watching for signs of tiredness such as yawning or sore eyes is only half of the equation.

“Young people often don’t feel tired when they take off in their car – certainly not ‘fatigued’. You wouldn’t say you were fatigued if you felt capable of mountain climbing. But this doesn’t mean you are not at risk of falling asleep behind the wheel. You have to be aware of how much sleep you have had and if it is enough to be driving safely, particularly on a long boring stretch of road.”

It’s also important to know that you will most likely and easily fall asleep between 2am and 6am and in the mid afternoon, around 3pm or ‘siesta time’. These are biologically primed times for sleeping.

Professor Lack believes we should have the same attitude towards sleep deprivation and driving as we do about alcohol and driving.

“If you fall asleep at the wheel from sleep deprivation and cause a major car crash, you really are as responsible as if you’ve driven under the influence of alcohol or drugs,” he says.

Warning signs

If you have any of the following warning signs when you are driving, you are at risk of having a microsleep at the wheel. You need to stop and rest.

  • Yawning
  • Poor concentration
  • Tired or sore eyes
  • Restlessness
  • Drowsiness
  • Slow reactions
  • Boredom
  • Feeling irritable
  • Making fewer and larger steering corrections
  • Missing road signs
  • Having difficulty staying in the lane

A potent scenario

Maybe you are driving and don’t have any signs of sleepiness.

You feel fine. You could still be at risk of falling asleep at the wheel. In fact, certain scenarios will put you at high risk. Here is a classic example:

  • Friday 11pm – You go to bed and have a great sleep until 7am.
  • Saturday – You go to work, study, wash the car, play sport, hang out with friends, whatever. There is certainly no napping!
  • Saturday 11pm – You are partying with friends. You party into the night and decide to drive home around 4am.
  • Sunday 5am – You are driving along the final stretch of road before you start making final turns into your own street. Even if your blood alcohol level is nil, you are now at very high risk of having a microsleep. If you’ve had a couple of beers, the risk is higher again.