Exploring sleep heart rate variability: linear, nonlinear, and circadian rhythm perspectives.

Background: Heart rate variability (HRV) is believed to possess the potential for disease detection. However, early identification of heart disease remains challenging, as HRV analysis in dogs primarily reflects the advanced stages of the disease.

Hypothesis/objective: The aim of this study is to compare 24-h HRV with sleep HRV to assess the potential utility of sleep HRV analysis.