Do A+ grades (as an undergrad) matter at all for graduate school? If I get A+ grades then it will raise my GPA in my undergrad institution, as well as for Columbia which is where I want to go to graduate school for statistics. Should I try hard to get A+ grades or should I be content with As? Trying for A+ grades would not cut into any of my important academic activity such as research or my other classes because I already make all As, but it might slightly affect sleep and socialization.

Edit (from answer): To be clear I am an undergraduate right now.
If your undergrad school awards more GPA points for A+ rather than As then you should definitely try to get A+. As a matter of fact, you should always be trying to do your very best anyways. But for a top program this will be especially important. If you go to grad school, academia will be your full time 9-5 Mon-Sat job, so I would say go on and start early. treat your subjects that way in undergrad and excel in every way possible so as to get into the very best program possible.