Untreated sleep apnea doesn't just mean that the patient doesn't sleep well, with the fatigue, crankiness, and mental fogginess that that entails. No, people with sleep apnea are also at greater risk for heart attacks and a long list of other health problems. People with sleep apnea aren't OBVIOUSLY sick, but they really do need treatment, or they will become obviously sick. And anything that might cause death is a pretty serious complication in my book!