Got enough sleep but woke up feeling groggy and tired? Had a hard time waking up until later in the day? Became sleepy when you stopped moving and/or sat for extended periods of time? You may have low Nitric Oxide.
A good average HRV varies on age, gender, and fitness level. Higher numbers (more variable/erratic heart beats, less consistent) have been seen to both improve and track wellbeing, fitness, and health. Does your HRV score match up?