Fatigue is the feeling you get when your energy level is low, and you feel weak.
You may feel fatigue when you do not have enough sleep or after a period of physical or mental exertion.
Your chances of being in a collision increase when you are tired. Your concentration will be poor, and your reaction times will be too slow.
Even though you may believe that you can drive while you are sleepy, you may not be able to keep the control of your body that needs sleep. You can fall asleep while driving, which is very dangerous.
If you are driving and begin to feel tired or drowsy, leave the roadway and find a safe place to sleep.