You don't have to be in the all-nighter if you don't want to, but it'd be nice of you to drop in and talk for a bit, it's what everyone else does.
Just a few minutes if you wish, as long as you want. That's the whole idea of the All-Nighter, not to stay up all night, but just hang out and talk and stuff during the night. Some of us actually do stay up all night, and some of us, who aren't in the Continent of North America, just pop in at any time and chat for a while.