Some games have rules about resting and recovering, in which things happen in full at certain times. (Often at the completion of the rest period, rather than midnight as shown here.)
Get 8 hours sleep? Get all your expended spells back. Get less than 8 hours? No spells for you!
You could make rules that give characters partial benefits from partial rests. But then you tend to get into ridiculous bookkeeping and number crunching that is no fun. So that's why most games ignore that and just award full rest benefits at a single discrete point.
Commentary by memnarch (who has not seen the movie)
Rey certainly seems to have woken up quickly. Mind you, there could be a lot of blinking and yawning that gets lost in the transition to comic panels. I'd be yawning a fair amount if someone had just woken me up gently, even if I was trying to sleep lightly to catch movement around me.
So could this be the start of actual training in the movie then? It doesn't seem like the best time to start it if so. Waiting until at least the light is starting to get brighter would seem better to me. People need their sleep even if they've got an early start to the day, plus it'd be a good sign of things starting to look up for once! Or maybe it's a directing decision to have the night lighting to go with a more somber feel? I'm not sure what there is to be somber about besides the Resistance getting constantly hammered however, and that's happening on the other side of the movie.
It's amusing to think that this game system has resting patterns based on the time of day on the planet the players are currently on as the default. Since there's basically no time spent traveling between systems longer than, say, a trip to the local convenience store, someone like Pete could probably plot out an optimal system to use that fact. Train or adventure a bunch, hop on a spaceship to the closest named location that'll hit midnight after arrival, refresh in less time, and continue with the training/adventure! Definitely something that could use an alternate rule or house-rule I think.
Luke: Rey, wake up.
Rey: What? What is it?
Luke: R2 and I think that Nute fears the Force. We need to get you trained quickly and heading back to find out why.
Luke: You may be the Resistance’s last, best hope.
Rey: I know all this. Why’d you have to wake me up?
Luke: You didn’t know it in character.
Rey: That’s a lame reason.
Luke: I figured you’d want extra time to get in your Stamina training.
Rey: Is it after midnight?
GM: <roll>... Just.
Rey: Great! I’m fully rested for the new day!
GM: I really need to house-rule that.