Nocturnal blood pressure (BP) surge in seconds (sec‐surge), which is characterized as acute transient BP elevation over several tens of seconds, could be a predictor of target organ damage. However, it is not clear that the severity of sec‐surge is different between sec‐surges induced by sleep apnea (SA) (apnea/hypopnea detected by polysomnography (PSG) or oxygen desaturation) and those induced by non‐SA factors (rapid eye movement, micro arousal, etc.), and sec‐surge variables associate with left ventricular hypertrophy (LVH) independently of conventional BP variables. The authors assessed these points with 41 patients (mean age 63.2±12.6 years, 29% female) who underwent full PSG, beat‐by‐beat (BbB) BP, and cuff‐oscillometric BP measurement during the night. All patients were included for the analysis comparing sec‐surge severity between inducing factors (SA and non‐SA factors). There were no significant differences in the number of sec‐surges/night between SA‐related sec‐surges and non‐SA‐related sec‐surges (19.5±26.0 vs. 16.4±29.8 events/night). There were also no significant differences in the peak of sec‐surges, defined as the maximum systolic BPs (SBPs) in each sec‐surge, between SA‐related sec‐surges and non‐SA‐related sec‐surges (148.2±18.5 vs. 149.3±19.2 mm Hg). Furthermore, as a result of multiple regression analysis (n = 18), the peak of sec‐surge was significantly and strongly associated with the left ventricular mass index (standardized β = 0.62, p = .02), compared with the mean nocturnal SBPs measured by oscillometric method (β = −0.04, p = .87). This study suggests that peak of sec‐surge could be a better predictor of LVH compared to parameters derived from regular nocturnal oscillometric SBP.