Inhale, heart speeds up; deep exhale, heart slows down. Why?

[Scruloose]

I’ve noticed that when I take a deep breath in, my heart rate will get faster. When I slowly exhale, my heart rate slows down drastically, and stays low for a few moments afterward, then returns to normal.

Is this common? What’s going on in there that causes this to happen?

[purpler]

Heart-Rate Variability (HRV) is completely normal, though in some people this effect is more pronounced than in others. Here’s a page with some technical info about it:

http://www.bio-medical.com/news_display.cfm?newsid=27

The rhythm of the heart is primarily under the control of the vagus nerve, which inhibits heart rate and the force of contraction. When we inhale, the vagus nerve activity is impeded and heart rate begins to increase. When we exhale this pattern is reversed. The degree of fluctuation in heart rate is also controlled significantly by regular impulses from the baroreceptors (pressure sensors) in the aorta and carotid arteries.