Ace 2 tracking sleep when not worn?

[Sarah-epieikes]

Is this possible? My son is adamant he tried to trick us into thinking he had zero sleep last night by taking his Fitbit off. It was on his shelf, he says. 

His Fitbit has registered sleep . I do not think it is physically possible for it to register anything when it is off the wrist. 

There are no periods of restless sleep or wakings, which is very unlike him, so the reading stands out.

Please help me be sure of my ground!

Moderator edit: subject for clarity

[LiliyaFitbit]

Welcome to the Fitbit Community, @Sarah-epieikes. I am sorry for the delayed response.  

I appreciate your participation in the Forums and sharing your concern about the Ace 2 tracking sleep when not being worn. I am glad to assist you with that. Ace 2 tracks several sleep metrics including when you go to bed, how long you're asleep, and how long you spend awake or restless. When your body is completely at rest and you haven’t moved for about an hour, the Fitbit device records that you’re asleep. Since you mentioned that there are no periods of restless sleep or wakings, it seems that the Ace 2 tracked sleep when your son didn't wear it, however it is not an expected behavior. I recommend wearing the device in a snug wristband while sleeping. For more information about tracking sleep, please see this help article: How do I track my sleep with my Fitbit device? 

I recommend restarting the tracker by following the steps at How do I restart my Fitbit device? Please monitor the tracker after that and let me know how it goes. 

Keep me posted on the outcome. I'll be around if you have any additional questions.