It is first advisable to find out what exactly is fatigue. Fatigue is any feeling where the body gets tired and drained of all energy. Sometimes this phenomenon is gradual sometimes it is sudden. This feeling of tiredness is normal after a period of prolonged exercise but if it happens for no apparent reason at all then a doctor must be consulted following which he will conduct some tests to ascertain the actual underlying conditions.
There are devices like the SOS Fatigue and the SOS Fatigue Pro anti sleep headset which are tools or Anti Fatigue Devices which aid in the prevention of falling asleep so that one remains alert, wide awake and full of concentration. When a driver is falling asleep an alarm will go off when the driver is dozing off with his or head tilting. The alarm will either only vibrate or ring or if set accordingly both will happen simultaneously.