Yes it's normal! I stay up like all night and eat all day now that it's summer! If you're worried about gaining weight because of this, just do some sit-ups or push-ups everyday, something simple. Maybe run a little bit XD
i wake up at like 2 pm during summer due to sleeping late like you, and i ended up losing weight .. but it depends on your body i guess, if you really are worried about gaining weight, don't eat much past 6 pm.