I had it set to Do Not Disturb last night and lost only 4% battery. We will see if it does the same tonight, too. It seems to get better for a day, then drain again.
I noticed that it shows "awake" after I've already fallen asleep, so I was confused by that.
If I don't turn on airplane mode, I'll keep it on silent because my phone vibrates with notifications from various social media and text messages all night.