The context of the following conversation is After a long night of drinking and feeling exhausted, Ash got home.:
Ash says I need to get to bed asap. I've got to sleep..
The friend responds You look terrible!.
Ash responds Yeah, I've been drinking all night and I can barely keep my eyes open now. I'm going straight to bed..
The friend responds Make sure you drink some water before you fall asleep, or you'll get dehydrated and your hangover will be worse in the morning..