On what basis is the Sleep score calculated?

[SunsetRunner]

I learned that there is no API to obtain Sleep Score. I had no choice but to try to self-calculate it from the Sleep Web API data, but when I checked the Community, I found that the calculation formula is not disclosed either. To make matters worse, there was no clear indication of the supporting papers or the reliability of the scoring (e.g., correlation with PSQI was found).
Is the Sleep Score calculated by Fitbit a scientifically meaningful value? If not, I am considering creating some sort of evidence-based calculation program myself.

[Guy_]

Hi @SunsetRunner - from experience it seems editing the sleep duration can affect the score.

It is an internal calculation based on duration in relation to the goal, and the various stages and duration and patterns, possibly combined with heart rate and breathing rate (and even basic oxygen levels, as used in EOV).

It might be quite hard to evolve a meaningful value but a relative one should be as good (to compare nights).