Sleep Deprivation.

Here's things that babies do:
-Eat
-Poop
-Pee
-Cry
-Look around
-Make faces that indicate one of the above

That's pretty much it. I think the goal is to get the balance to an equilibrium that you would like.

For us, the daytime balance involves a lot of eating and sleeping, but the nighttime alloy is heavier on crying and looking around. Their starting to really show some different personalities though. Neither one is all that interested in letting mom and dad rest much between the hours of bar-closing and walk-of-shame.