I have been traveling to India since I was little and at about age ten, I figured out how to completely get rid of my jet-lag. My dad (pictured above) however, is still trying to master the process.
Step 1: Change Your Internal Time
The main reason many people get severe cases of jet-lag is because their body is still on a different time zone. To avoid this, the first thing I always do as soon as I get on the plane is, I look at the current time at my final destination. For me, that was Nagpur, India (I have the Mumbai time pictured, but they are in the same time zone), and as shown in the image, it was the middle of the night. This meant that I should immediately sleep on the plane for as long as I could.
This is the most important step. Many people may see the entertainment screen and immediately decide to watch a movie or two. BAD MOVE. This will keep you up when you should be sleeping.
Step 2: Sleep As Well As Possible
Take all the steps to get the best sleep possible. Close the window shade to reduce light, use a blanket to keep yourself warm and a pillow to stay comfortable. One of the other things that I do to make sure I don't end up sleeping on the shoulder of the person sitting next to me is using the headrest. As pictured above, most headrests (on both domestic and international planes) are bendable so you can kind of make a barrier to prevent leaning when sleeping.
Also, before going to sleep, make sure to drink some water...BUT NOT TOO MUCH! Just enough to keep you hydrated (the air on airplanes is very dry). If you drink too much water, you will have to go to the bathroom in the middle of your sleep cycle and going to sleep is sometimes harder the second time.
Step 3: Wake Up!
Time is a weird thing when traveling between time zones. You may end up waking up once in a while when you should still be sleeping, but don't allow yourself to fully wake up until it is morning at your final destination.
When you do wake up, you can take full advantage of the entertainment system that I know you've been waiting hours to play with.
Side note on food:
Usually airlines serve the first meal on time zone you are leaving from and then the ones thereafter on the time zone you are going to. Sometimes food can interrupt your sleep cycle. I tried to eat when they served me, and if it was in the middle of my sleep cycle, I would immediately go back to sleep afterwards.
Step 4: Arriving at Your Final Destination
This is probably the hardest part of the whole process. For me, I arrived in Nagpur, India at 8:30am which means I had a full day ahead of me that I had to stay awake.
**If you are arriving in the evening, this means, according to the previous steps, you have been awake for a while. If you are not feeling sleepy (which is unlikely), try drinking some decaf tea and disregard the rest of this step**
1. First things first, eat a meal, BUT DON'T over eat! Eating a small meal will help your body stay awake but eating too much will send you into a food coma (from all the good food of course) and then your fight to avoid jet lag will officially be over.
2. Keep yourself busy! Go for a walk, talk to people, play an interactive game but for the love of all things good in this world, DO NOT SIT DOWN AND SPEND MORE THAN 5 MINUTES ON YOUR PHONE (or computer)! You will immediately feel the drowsiness and it will take everything you have to not fall asleep.
My cousin took me shopping in the evening to keep me busy and that worked wonders!
Step 5: Officially Beating Jet-lag
Once you have made it through the day and evening you can finally go to bed. It is ok to go to bed somewhat early (I think I went to bed around 9 or 9:30 pm the first evening). But don't go to bed earlier then 8:30 or you will most likely be waking up pretty early the next morning (unless you can sleep for a solid 12 hours, in which case GO FOR IT!)
After that initial night of sleep you should be set for the rest of your trip!
Good luck and safe travels to all of you!