Sleep Not Logged if Sleeping Sitting Up

[Spleepless]

Why is my sleep not logged on an Alta when sleeping sitting up or propped up in bed? It won't log the sleep hours until I lie flat. It significantly reduces the number of sleep hours it counts each night.   Thanks!

[SunsetRunner]

The tracker automagically tracks sleep when laying still for about a hour. When sitting and not moving much for a longer time (playing console games, sitting in a train, bus, reading a book..?).. it could then be detected as sleep while not sleeping.. 

[gcolon58]

Interesting.  I've been noticing that my Alta doesn't accurately calculate my sleep time as well.  I know I'm not laying flat on the bed.  My pillows do elevate me from my shoulder up; and I place my hands are under my face. 

[MackemMike]

I've noticed it tends not to track this, like if i fall asleep on a plane. Likely < 1 hour and probably some movement. Thx.

[JBS2]

I just bought a wedge for my back and this has caused my fitbit to not track my sleep....When I lie it tracks very well...