Answer:

Until recently, people who slept on trains were mostly businessmen, but the younger people now have also begun to sleep on trains. This is due in large part, especially in the cities, to the grueling and long commute to work and to school. A commuting time of an hour or more one way is not uncommon in large cities such as Tokyo and Osaka where one’s place of work or school is often located quite a distance away.

Businessmen get on the average, less than seven hours of sleep a night. The train becomes a most suitable place to rest for overworked businessmen and students cramming for exams, both who suffer from chronic lack of sleep.

It is the perfect place with heating in the winter and air–conditioning in the summer. Heat coming out from under the seats in winter is enough to make anyone feel drowsy.

Stopping for a drink after work and returning home slightly intoxicated inevitably causes one to fall asleep on the train the minute one hits the seat.

The safety of Japanese trains is another reason that can be cited why people can fall asleep feeling safe and secure. Although it has become a little unsafe now, bags and wallets are rarely stolen from slumbering passengers.

Also the large intake of carbohydrates in the Japanese diet makes the Japanese fall asleep on trains. It takes a little longer to digest carbohydrates which brings about drowsiness.