This 7 minute talk by Jakob Larson is excellent. He reviews 7 years of tracking resting heart rate and is using Oura ring data for a portion of that. Key take-away points are elevated RHR can be used a predictor of illness and stress. Eating late, exercise and alcohol will effect RHR.

Via Quantified Self:

Briefly, by tracking his RHR over a long period of time, Jakob has developed an intuition for connections between his RHR and physiological state. He’s able to use the data to tune his self-awareness, but still keep a safety net when unexpected RHR elevations might portend a flu. To boot, the years of data across the Fitbit Blaze, Oura ring and Basis are one of the most extensive within-individual comparisons I can find anywhere of these devices.