Fatigue is usually described as tiredness, weariness or exhaustion. Our natural rhythms programme us to be awake during the day and asleep at night. It’s more than feeling drowsy and results in reduced ability to concentrate, react quickly and make good decisions.
Problems occur if this rhythm is disrupted, particularly if we lose sleep. A person needs about 8 hours sleep per night. When you sleep fewer hours, a sleep debt accumulates. The only way to reduce sleep debt is by sleeping! Fatigue can be caused by many things, e.g., monotonous activity, shift work, extended hours, stress, family commitments, illness, etc.
Falling asleep at the wheel is at the extreme end of driver fatigue, because your driving can be impaired long before you nod off. Driver fatigue is extremely dangerous as it reduces the driver’s ability to judge his or her own level of fatigue.
Microsleeps are brief, unintended episodes of loss of attention, often signaled by a blank stare, head snapping or prolonged eye closure. These can happen when a person is fatigued and trying to stay awake to do something monotonous (like driving). During a microsleep, a person will not respond to outside information (like a red light or a curve in the road).
The more sleep debt a person has, the greater the chance that microsleeps will occur. Other symptoms include yawning, poor concentration, tired eyes, restlessness, slow reactions, boredom, feeling irritable, making fewer and larger steering corrections, missing road signs and having difficulty staying in the lane.
As noted above, driver fatigue is not simply related to the number of hours spent driving. This is why many fatigue-related crashes happen during road trips less than two hours long or within 20 minutes of home. Because of the natural rhythm, it is more dangerous to drive between 1am and 5am than at any other time of the day.
If you drive after staying awake for 24 hours, you are as dangerous as someone with the blood alcohol content of 100 mg/100ml (the New Zealand limit is 80mg/100ml).
Download “Rest Easy’ – your guide to minimizing driver fatigue and enjoying the rest areas of the Central North Island.