Save power when my device knows I’m away
It’s just a while when your tablet (or laptop) went to Sleep mode, but you remembered that you forgot to finish some work. You want to wake your machine up and you expect that it will be quickly. But you have to wait because meanwhile Windows went to hibernate. You think for yourself “How it’s possible? I turned the hibernation off – I never wanted to use it.” but it seems Windows did it regardless of your settings. Frankly, didn’t.
Probably you have turned on (it’s by default) setting “Save power when my device knows I’m away” (formerly “Save me power when Cortana knows I’m away”) – in Settings » System » Power & sleep. Just turn this setting off and you’re done.