Why do overseas flights leave in the evening and arrive in the morning?

I've noticed most flights to Europe from North America leave evening's around 6:00 and arrive in the morning at the destination. Why is it like this. This makes Jet Lag far worse because you arrive early in the morning like 3:00 am which can be tiring. It doesn't make sense that flights are like this, they increase jet lag so much more. Like if it left in the morning it wouldn't be as bad and you wouldn't be as tired on your trip.