SKNA and HR during wakefulness and different sleep stages. Plots A, B and C compare aSKNA, SKNA burst area and HR, respectively, between OSA patients and controls during wakefulness and different sleep stages. aSKNA and HR were expressed as scatter plots with mean (horizontal lines) and standard deviation (whiskers) and SKNA burst areas were expressed as scatter plots with median (horizontal lines) and interquartile range (whiskers). *p<0.05 vs control group; #p<0.05, ##p<0.01, ###p<0.001 vs Wake. aSKNA, averaged SKNA; HR, heart rate; N1, N2 and N3, non-REM sleep stage 1, stage 2 and stage 3; OSA, obstructive sleep apnea; R, rapid eye movement sleep (REM); SKNA, skin sympathetic nerve activity recorded by ECG patch electrodes; W, wake.