Ironically, I think getting more sleep will help you out more.
I'm in art school right now, so while I don't have to deal with kids, there are many days where I'll only get less than 5 hours of sleep. And I'll have to say, I'm much less productive and draw shitter when I don't have sleep.
I've had a friend who pulled 3 all nighters in a row, and she started hallucinating. Seriously not healthy for you, so I do not recommend not getting enough sleep.
But I have a bad habit of doing it anyways D:
But in terms of tricks, it's going to be different for everyone. Coffee doesn't actually do much for me (although I pretend it does cause, ya'know, popular culture) so taking a shower when I get sleepy will wake me up because of the shock of the water. Taking 20 min naps in-between helps too.
Again, not something you'd want to do often. Alternately you could try to cram drawing whenever you can: like while taking the bus, while waiting at an office... etc.