On a long flight, I can sleep peacefully. But while commuting, I hate to fall asleep. What is behind this hatred is the fear of missing to get down at the destination. My commute time went up as soon as I moved from La Defense into Paris. Ever since, I have been falling asleep while commuting more often.
Luckily for me, the longest and peaceful leg of my commute, where I usually fall asleep, is between the terminal points of a train. Once I was in my own world listening to the music that I forgot to get down. The woman next to me double-backed after getting off the train and gently shook me to bring me back to real world. Another time, I was asleep and a kind soul knocked on the window to wake me up. All these experiences has not made me alert. In fact, I fall asleep more often now.
There are others who fall asleep during the commute. My friend is one of them. But he has a simple way to wake up. He sets the alarm on his clock to wake him up before his destination.