Fitbit accurately logged nap when I wasn't wearing it

[tunolno1]

I took my Fitbit, versa 2, off this afternoon before a nap. I don't normally take it off, I just didn't want it to buzz for notifications and in my tiredness taking it off was easier than adjusting the settings. Anyway, as the title says, I left it off well into the evening. When I looked at the app much later, it logged the nap, accurately. I'm a little bit creeped out. Has anyone experienced this or know how this could happen?

[LZeeW]

Hello @tunolno1 and welcome to the Community.  The green LEDs are supposed to turn off when you aren't wearing your Fitbit.  If you set it down so that the light gets reflected back from the overlapping watchband or something else, the lights don't turn off and your Fitbit senses a totally fake heart rate.  Heart rate plus no movement equals sleep.  Don't be creeped out.  Your Fitbit wasn't reading your mind.