My partner and I are getting older, and sleep in different rooms at different times. We've both worried about the other dying unbeknownst. I wear a pulse watch, but don't know if it will do what I want. Any ideas, friends? I'd like us to be able to glance at a screen and see a heartbeat, ideally without spending more than a couple hundred dollars, and without too much hassle or cumbersome equipment. I appreciate any suggestions. (edit - we use android and Linux.)