Morning heart rate variability was strongly associated with its absolute (P<0.0001) and relative (P<0.01) diurnal changes, but not with chronotype (P>0.09) in healthy young men.
Observational (n=23)
Does morning heart rate variability predict its diurnal change or associate with chronotype in healthy young men?
In healthy young men, morning heart rate variability is a strong determinant of its diurnal variation, whereas chronotype shows no significant association.
p-value: p=<0.0001
Whether morning heart rate variability (HRV) predicts the magnitude of its circadian variation in the absence of disease or is influenced by chronotype is unclear. We aimed to quantify associations between (1) morning HRV and its diurnal change, and (2) morning HRV and a Morningness−Eveningness Questionnaire (MEQ)-derived chronotype. Resting electrocardiograms were obtained in the morning and evening on separate days in a counterbalanced order to determine the mean RR interval, root mean square of successive differences (RMSSD), and standard deviation of normal-to-normal RR intervals (SDNN) in 23 healthy men (24.6 ± 3.4 yrs; body mass index: 25.3 ± 2.8 kg/m2). The MEQ was completed during the first laboratory visit. Morning RMSSD and SDNN were significantly higher (Ps 0.09). Morning HRV was a stronger determinant of its evening change than chronotype. Greater diurnal variation in HRV was dependent on higher morning values. Strategies to improve basal HRV may therefore support healthier cardio-autonomic circadian profiles in healthy young men.
Vondrasek et al. (Wed,) conducted a observational in Healthy (n=23). Morning heart rate variability and chronotype was evaluated on Associations between morning HRV and its diurnal change, and morning HRV and MEQ-derived chronotype (p=<0.0001). Morning heart rate variability was strongly associated with its absolute (P<0.0001) and relative (P<0.01) diurnal changes, but not with chronotype (P>0.09) in healthy young men.