Both the Lief and the Polar H10 + Elite HRV app offer best in class continuous heart rate variability monitoring. However, they both excel in different areas when it comes to stress and anxiety relief, customized breathing, sports performance, and others. In this video I answer the question: "which continuous heart rate variability wearable should I buy"?

LIEF: discount link https://getlief.com/?af_code=HRVHACKE... and Full review:    • Lief Review: Improve your Breathing a...  
Polar H10: https://amzn.to/3XgSt0r
Elite HRV: https://elitehrv.com/

HRV or Heart Rate Variability is a very strong determinant of how well you are handling emotional or physical stress at any given moment.
Please note: Neither device is capable of 24hr monitoring as the Lief needs to be charged overnight while the Polar needs to be occasionally manually synced with the Elite HRV app throughout the day. Using an Oura ring or similar clinically validated wearable to monitor your vitals during sleep is recommended.
If you are looking for a research paper that talks about different heart rate variability tracking devices, which ones are capable of continuous readings check out: https://www.mdpi.com/1424-8220/21/4/1...
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