Changes in RR, QT, and QT prolongation corrected for heart rate (QTc) intervals while awake and during non-REM [Stage 2 and slow wave (Stage SW)] and REM sleep in patients with LQTS with or without OSA and control subjects. Data are least square means ± standard error of the mean. *Adjusted P < 0.05 for comparison between patients with LQTS with and without OSA. LQTS, long QT syndrome; OSA, obstructive sleep apnea; REM, rapid eye movement.