Polar Nightly Recharge API
Nightly Recharge™ is a recovery measurement that shows how well your body recovers from daily training and stress. It is based on heart rate variability (HRV) and overnight heart rate data. The higher the Nightly Recharge score, the better your body has recovered. For more detailed information please check [Nightly Recharge](https://support.polar.com/e_manuals/unite/polar-unite-user-manual-english/nightly-recharge.htm).