I’ve fallen asleep on the subway many times myself, especially when I lived in Milan.

BTW I have a love-hate relationship with the NYC subway.

The Good: Frequent, express service, pretty safe, reliable.

The Bad: Door hogs (nobody wants to move in!), crowded, weekend track work, the A/C is generally VERY cold.

The Ugly: Getting trampled on by people desperate to get a seat during rush hour.