[olau]

If you're the father, sleep on the couch (or buy another bed). Then when you're more refreshed, you can try and help out the mother (I'm assuming breast feeding here).

If you're the mother, try really hard to get some kind of daily cycle induced in the baby. So minimize breastfeeding, chatting, other activity at night.

YMMV. Also you need to accept that you're going to be lacking some amount of sleep for years.