Sleep apnea is the most serious form of sleep disordered breathing. If you have it, your breathing may stop hundreds of times a night, forcing your brain to awaken partly to restore breathing. You are likely unaware that you’re waking up, or, if you are aware, you may attribute it to the need to urinate or nightmares. Left untreated, sleep apnea can lead to cognitive difficulties, heart problems, and metabolic disorders. Fortunately, many successful treatments are available.