Reminds me of Fitbit using heartrate to approximately guess calories used.

I'm told with a lengthy night on uppers can you can get your 24/hr burn up to the 7000-10000.

I was doing support for a fitness data aggregator where a partner reported an issue: a user logging 15k+ steps between 9pm and 4am with minimal location delta. Sadly I wasn't able to push a "stay hydrated" notification over our system to the user.