My recommendation is to avoid sleeping pills or too much sleeping on the flight. Read, watch movies, walk around the cabin, do anything to keep yourself occupied and limit your sleeping to short, occasional "catnaps." After arriving at 4 pm, you will take up to an hour getting through C&I, getting money, buying tickets into the city, etc. Then, the train into Tokyo is another hour+. That puts you in your hotel in the early evening. Go out for a walk, get some exercise, have a meal, do anything to stay awake and active until a normal bedtime - 10:00 pm or so. Then go to bed and get up at a normal time in the morning. If you have trouble sleeping, then take your sleeping pill but only to help you sleep at a "normal" time.

If you sleep too much before arrival or go to bed immediately after arrival, it will only make it harder to adjust to local time and you will find yourself awake at 3 am and falling asleep at 3 pm.

At any rate, the above is what works for me.

JR