DEAR DR. ROACH: How are sleep apnea, sighing and heart failure related? Recently, I was told that I have severe sleep apnea and that I must use a CPAP machine. I have noticed that during the day I frequently take a spontaneous deep breath. Is that sleep apnea while awake? I have coronary heart disease and have three stents. Will the CPAP machine help me in any way? -- A.P.
ANSWER: It's complicated.