> "because I feel sad for the nightouter when he picks up for the third guy"
Why not talk to the night-coder? The best bosses I have ever had were the ones who actively told me to work less. It's so rare to hear that in our industry that you may just earn yourself some real loyalty.
[edit] To clarify: the guy not pulling his weight is IMHO a separate issue from the guy who works at night. If the guy not pulling his weight is forcing other people to work more though, by all means don't let that happen. Then you have two problems on your hands instead of one.