Should heart rate drop while deep breathing ?

Should heart rate drop while deep breathing ?

Heart rate increases when you breathe in and decreases when you breathe out. This is due to a reflex regulation of the heart rate to counter the decreased blood flow out of the heart when you breathe in and increased outflow when you breathe out. If a deep breath is held, heart rate can decrease as it is like a Valsalva maneuver, which causes stimulation of the vagus nerve (10th nerve arising from the brain) and reflex decrease in the heart rate.