Fatigue is an overall feeling of tiredness or lack of energy. When you are fatigued, you have no motivation and no energy. Sleep apnea can interrupt you sleep as many as hundreds of times a night due to the closure in your airway during an apneic event. When your airway is restricted it signals your brain to wake your body up to restore your muscle and open your throat to breathe.
If your body is repeatedly waking itself up, you are not allowing yourself to go through the entire four-stage sleep-cycle therefore your body has not fully rested. When you don't enter the deep stages of the four-stage sleep-cycle your body has not been able to fully repair itself causing you to feel fatigued, constantly trying to catch up on your sleep.
Fatigue puts you at risk for accidents, both at work and while driving.
Studies have shown that use of continuous positive airway pressure (CPAP) can decrease fatigue and increase energy levels in patient by allowing them to reach all stages of the four-stage sleep-cycle.