There's something very lonely about not having access to IM in the evenings when everyone else does. Your mind teases you with the idea, whether or not it's fairly based in reality, that every night you're missing out on conversations you should be having and connections that you should be making.
I don't dwell on it... I happily wrap myself up in a book or turn on the TV, and forget until much later that I could have been connected to the larger world during those evenings. It's only in the looking-back that I add up the lost hours....