How Much Sleep Do Fitbit Users Really Get?
I'd take all of this with a giant pinch of salt. If the data is anything like the sleep data generated by my Garmin vivosmart HR+ it's not much better than garbage.It frequently counts me as sleeping when I sit down to watch TV in the evening, or read a book in bed. Sometimes I stay up until 1am reading and it always tracks me as deep sleep from 10pm when I got into bed. I usually take it off for my morning shower (It is waterproof, it just annoys me when washing) and it nearly always counts the walking from bed to shower as a few minutes of restless sleep and the shower itself as deep sleep.I'm not sure how it makes an assesment of my sleep level. I don't know if it's just based on movement or if it takes heart rate data into account but it does have a heart rate sensor. It seems to usually be wrong.In theroy it would be possible to know about these limitations and adjust your use of it to make it more accurate, but unless the participents of the study are aware of that and have been manually correcting the data then that won't be the case.(Not a general critisim on the device, I like it for everything else, but it's sleep data is clearly rather inaccurate)