Yes me too! It definitely feels like something I trained myself into during my teens. I don't know why but I guess the quiet time lead to contemplation of all my teenage troubles. I do the same on bus rides since I used to catch the bus for school every day and had one of the longer rides. The problem is I actually enjoy it so it's hard to stop.

I also drift off and notice it and jerk wide awake. Sometimes with hypnagogia, shadows take the form of bad people or I see spiders hovering or running across my vision. It's a bit disturbing and definitely doesn't help when I get an adrenaline response. I seem far more prone to it when I'm very tired and parts of my brain are shutting down but this one stubborn conscious area keeps me up.