The respiratory system is directed affected by sleep apnea. It is the system that is struggling to function properly without treatment. As the body is unable to breathe continually throughout the night it is also losing oxygen.
This lack of oxygen may become apparent during the day. If the person already suffers from a condition like chronic obstructive pulmonary disease or asthma they may find their symptoms worsening.
As a person exercises, even if they do not have COPD or asthma, they may find themselves unable to catch their breath. Exercising can become extremely difficult as they are not able to breathe properly.