This observational study aims to compare heart rate variability (HRV) parameters obtained from different analysis durations in healthy adults and to examine how these parameters relate to resting blood pressure values. HRV is a noninvasive measure commonly used to assess autonomic nervous system activity. Standard short-term HRV analysis is typically based on 5-minute recordings, but shorter and longer analysis durations are also used in research and practice. This study will evaluate whether HRV values derived from 1-minute, 5-minute, 10-minute, and 20-minute analysis windows differ from one another and whether their relationships with systolic blood pressure, diastolic blood pressure, and mean arterial pressure change according to analysis duration. Participants will attend a single study visit. After a rest period, resting blood pressure and pulse will be measured, and a continuous HRV recording will be obtained using a chest strap device. The study is designed to provide methodological information on the comparability of different HRV analysis durations under the same physiological conditions.