Suggestion:
Add ability for user to overlay onto graph Heart rate & Stress; Heart rate/Respiration; and others. Ability of multiple overlays would be awesome.
Ideal: ability of picking/choosing any tool in My Day with any other tool. I realize some overlays may not seem ideal, yet, each user has his/her own idea of need for data so allow users to pick and choose.
Example is how Connect allows overlays in "Sleep" category and in Landscape format.