Note that this does vary from person to person. I know people who can sleep anywhere but I personally find it very difficult to sleep sitting up. I pretty much

Note that this does vary from person to person. I know people who can sleep anywhere but I personally find it very difficult to sleep sitting up. I pretty much never sleep on planes, for example, no matter how little sleep I've had or how long the flight is. So in this commuting situation I would try to sleep, but probably only be asleep for half the time and never get to the REM stage.