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3107 2013
Drowsiness: Excessive tiredness or sleepiness

Tiredness can be simply a matter of an over-busy lifestyle, or it may be the symptom of a serious medical condition. Note that for tired symptoms, it is important to specify whether they are from lack of sleep (see drowsiness), or whether they refer to physical or muscular tiredness (see fatigue or weakness). In some cases, these two categories may overlap or cause each other.

Virtually everyone is at risk of drowsy driving, especially those who are deprived of sleep, driving long distances without rest breaks, driving through the night or at other times when they are normally asleep, taking medications that increase sleepiness or drinking alcohol, driving alone, driving on long, rural, boring roads, and those who are frequent travellers

Driving drowsy is the same as driving drunk. You're very impaired, your judgment is impaired, your reaction time is impaired, your memory is impaired. And this huge sleep debt you've accumulated suddenly seizes you, and that's when people die," states Dr. Dement. He also stresses that drowsiness is not a warning sign, it is the last thing that happens before you fall asleep, whether you want to or not.

The above slogan on road side signs warn of a very serious road safety risk.
But what is drowsiness?  Is it different to fatigue? 
Fatigue and drowsiness are often considered to be the same thing. 
Fatigue is the feeling of being physically tired, lacking energy or strength or mentally drained or exhausted. It is not necessarily the same as feeling sleepy or drowsy. However, the term “fatigue” is in common use and may mean many things, including drowsiness (sleepiness), lethargy, tiredness, malaise, listlessness, or weakness.
While physical fatigue can be a distraction and can reduce a driver’s concentration, the greater risk for drivers is drowsiness. Going to sleep at the wheel of a motor vehicle is the cause of around 20 per cent of fatal road crashes Australia. 
Studies show that a person who has been awake for 17 hours faces the same risk of having a crash as a person who has a BAC of .05.  At .05 BAC a driver is twice as likely to have a crash as a driver with a .00 BAC. 
The cause of drowsiness is sleep debt.  If you do not get enough sleep, or the quality of your sleep is poor, you build up sleep debt.  This is common for many drivers but particularly so for people who suffer from sleep apnoea.
Do you suffer from sleep apnoea?
Does someone close to you complain about your constant snoring or restlessness during sleep?  Do you often wake during the night, gasping for air?  Are you always tired and often go to sleep while sitting quietly in front of the TV or at your desk?  You may have sleep apnoea.
Sleep apnoea is a condition in which breathing stops momentarily during sleep.  It is caused by the throat and tongue collapsing during sleep and blocking the airways.  In Australia, about 25 per cent of men over 30 years of age experience some degree of sleep apnoea.
Breathing can stop for 10 seconds or longer causing you to wake, gasp for breath, then fall asleep again. Often the cycle is continuous causing a fragmented sleep thus sleep debt.  

Extreme drowsiness during the day is a symptom. When sleep apnoea is severe, the risk of falling asleep while driving is greatly increased.  Poor concentration and irritability may also result.
The only way to repay sleep debt is by sleeping.
So what are the signs that you are drowsy?
• Sore or heavy eyes – you just want to close them
• Zoning out – eyes are open but the mind is blank
• Micro sleeps - brief loss of attention or light sleep
• Constant yawning
• Drifting in the lane
• Over-steering
• Poor concentration restlessness
• Trouble keeping you head up
• Mood changes – irritability
• Difficulty remembering the last few kilometers
• Variations in driving speed
How do you deal with drowsiness?
• Make sure you regularly get enough sleep
• Seek medical attention if you frequently feel sleepy
• Don’t start a long trip after a long day of work or at a time you would normally be sleeping
• Plan your trip with regular breaks – a fifteen minute break every two hours of continuous driving
• If you feel tired, stop the car and have a power nap.  A power nap of 15 - 20 minutes will help but any longer and you will enter a deep sleep and perhaps feel worse when you wake.
• Remember, a power nap is only a temporary refresher.  At some stage very soon you will need to have a proper sleep.
• Be aware of the drowsiness effects of any medication you take.
To get a more informative explanation of this topic view our training video about drowsiness with a segment presented by Dr Murray Johns, Founding Director of the Sleep Disorders Unit at Epworth Hospital, Melbourne.

Go to  From the resources menu select: fleet-driver-safety and download the video “drowsiness-and-fatigue”