The frequency of cardiac arrhythmias in wake and sleep was studied in 18 patients admitted to a coronary care unit. No significant differences were found in the distribution of ventricular premature contractions (VPCs) or atrial premature contractions (APCs) in either wake or sleep. A tendency for ventricular premature contractions to occur more commonly during wake-sleep transitions than during sleep transition periods (NREM-REM) was noted but this did not attain significance.
Smith R, Johnson L, Rothfeld D, Zir L, Tharp B. Sleep and Cardiac Arrhythmias. Arch Intern Med. 1972;130(5):751-753. doi:10.1001/archinte.1972.03650050071013