What a cool project! I&#x27;m working with UCSF cardiology on various projects involving Apple Watch&#x27;s heart rate sensor, and here are a few applications you might consider for your technology:<p><pre><code>  1. Atrial fibrillation (you mentioned arrhythmias—this is probably the highest-impact heart arrhythmia since it causes about a quarter of strokes and is frequently undiagnosed)

  2. Sleep apnea (if you can also measure oxygen saturation)

  3. Heart rate variability for stress reduction or mindfulness.

  4. Tracking tachycardias from Adderall usage.

  5. Heart failure exacerbations (probably if paired with a scale)

  6. (Perhaps) other arrhythmias like supraventricular tachycardia or atrial flutter.
  
  7. Irritable bowel syndrome. Believe it or not, IBS is connected to heart rate variability via the action of the vagus nerve.

</code></pre>
There are also all sorts of non-medical, but fun, applications you could pursue. For example, rating which scenes in Game of Thrones get your heart pumping the most:
  <a href="http:&#x2F;&#x2F;blogs.wsj.com&#x2F;digits&#x2F;2015&#x2F;08&#x2F;13&#x2F;what-game-of-thrones-does-to-your-heart-rate&#x2F;" rel="nofollow">http:&#x2F;&#x2F;blogs.wsj.com&#x2F;digits&#x2F;2015&#x2F;08&#x2F;13&#x2F;what-game-of-thrones-...</a>