I wonder if there might be something more like avoidance? My brother (ADHD) would sleep through the bus every day. I went to another school at the time. But, a friend of mine mentioned that my brother was getting into trouble on the bus and seemed extra hyper. I mentioned this to him and he said he hated the bus — being in a close space with no escape and so many kids made him feel unable to be in control, and they the driver got on his case for how he behaved on the bus. So, it might be worth exploring if this is a bus/transition/1st class of the day issue versus a sleeping issue.