Sleep apnea is when your breathing is disrupted during sleep (usually from blockage of the airway). This forces your body to constantly wake up all night long in order to save your life. The most common cause of this is higher body mass leading to increased pressure around the throat especially when laying down.
Sleep apnea like this can be seen in football players, wrestlers, weight lifters, obese people, or anyone else with a very high body mass that can cause blockage of the airway.
We aren't talking about simply not sleeping much.
If you are noticing sleep apnea that has no relation at all to this, you need to go see a doctor.