I use the bus to go to school, and it takes about 4 hours for a round trip, so the time on the bus is very long.
I used to be very prone to car sickness, but it seems that I got used to it a bit..
No matter how much I slept on the bus, I didn't feel like I slept well, and I'm still tired from school.
You'll probably get used to it after a little while. lol