How to fall asleep easily in a car and train?

I'm taking a 3 hour car trip then a 2 hour train trip. I get VERY car sick. I even get car sick on the way to school! So the only way the car sickness doesn't bother me is by going to sleep. It usually takes me a while to fall asleep in a car-even if I take Dramamine! I am just wondering if there are any tricks or tips to fall asleep fast in a car (and train). Thank you.