Morbid obesity influences the nocturnal electrocardiogram wave and interval durations among suspected sleep apnea patients.

"CONFLICT OF INTEREST STATEMENT Lipponen JA is a shareholder of a company (Kubios) that designs ECG analysis and heart rate variability analysis software. Other co‐authors have nothing to declare."

"FUNDING INFORMATION This work was supported by the Research Committee of the Kuopio University Hospital Catchment Area for the State Research Funding [5041798 to S.S, 5041803 to H.K., 5041809 to S.N., 5101137 to J.L., and 507T044 to J.L.)], Seinäjoki Central Hospital (7746), the Competitive State Research Financing of Expert Responsibility Area of Tampere University Hospital (VTR7319 to A.K., VTR7312 to A.K., VTR7330 to A.K., and EVO2089 to A.K.), Tampere Tuberculosis Foundation (to A.K.). The European Union's Horizon 2020 Research and Innovation Programme (Grant 965417) (to S.N.)."