How does Snapchat know when you're sleeping?

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Tags

1. #state
2. #sleepy
3. #duration
4. #appearing
5. #knows
6. #people
7. #appear
8. #while
9. #armchair
10. #snoozing
11. #seemingly
12. #snapchat
13. #inactivity
14. #based
15. #sleeping
16. #asleep
17. #actionmoji