Statistics based on physiological cycles and not on midnight-to-midnight

[dado93]

The statistics of the cardiac and respiration module are computed using as a timeframe the time that goes from midnight to midnight. It would be interesting to offer two different functions for each of the statistic:

• get_daily_XX, computing the value of statistic XX from midnight to midnight (current behavior)
• get_cycle_XX, computing the value of statistics XX from bedtime to the following bedtime (physiological cycle)

Of course, in order to compute statistics on a physiological cycle level, we need to:

• have sleep data available
• define maximum duration for a physiological cycle (e.g., what happens if a user skips a night of sleep?)

https://support.whoop.com/s/article/WHOOP-Cycles?language=en_US

What do you think @Vaeliss ?

[Vaeliss]

Yes, agreed, I would expand this also to stress and activity modules in the future too. Essentially, I’d extend it to any metric that we can obtain as a series and then compute aggregates over time.

Perhaps we should consider adding a cycle_type parameter to any get_XX function, rather than creating different versions of the function. This parameter could be set to "physiological" (like WHOOP) or "solar_day" (or something like that, i.e. midnight to midnight); we could also consider including the choices "day" and "night" for the same parameter (i.e. while awake, while asleep). Then we can have 4 functions in utils that take as input any time series and filters / divides it based on the necessary logic (e.g. there's already utils.filter_out_awake). Seems to me cleaner than having multiple versions of the same statistic as a function?

Also, it seems reasonable to me to say that if a physiological cycle is longer than 36 hours, instead of having a very long sleep cycle we assume solar day cycles for those days (i.e. stops and start at midnight). And "night" statistics would be NaT.