At San Francisco's Health 2.0 last week, US brain health company Brain Resource premiered its new gadget that tracks your heart rate variability, or the rising and falling of your heart rate when you breathe in and out.

The device also assists you through a breathing technique while claiming to find the sweet spot -- that is, according to the company, the rate of breathing that will best slow your heart rate, calm your nervous system and get you focused and feeling good.

The device uses a small ear clip, which monitors your heart rate variability. Online and smartphone apps can help train users to "objectively track their heart rate variability over time," states the company.

The MyCalmBeat monitor retails for $79.95 (currently at a discounted launch price of $49.50) through the company website, and mobile apps are available through Apple, Android and BlackBerry.

A video illustration of how MyCalmBeat works

Other options to train your breathing are Azumio's Stress Doctor iPhone app, which also relies on your heart rate variability to calm frazzled nerves. Or try the customisable Breathe2Relax app, released by the US Department of Defense, which guides users through diaphragmatic breathing to control stress. Users can select settings for breath duration, number of cycles, as well as choice of music and background images for optimal relaxation.