One of the dreaded things about traveling, especially to the other side of the world is jet lag. If you get it bad, it is going to be a bad time, and it can really ruin your vacation, and ruin the time when you get home and have to get back into a routine. Living in the Boston area, I have been extremely lucky to have relatively short flights to Europe. With the longest being about 8 hours, and all of them tend to be overnight flights and arrive in Europe a little before noon, so jet lag hasn't really been a problem on those flights. Although both of my brothers got jet lag by taking a long nap after our arrival in Paris, so jet lag is possible, and that leads me to the key for "hacking" your body to avoid jet lag. (I'm not a professional by any means, but this has been working for me on all my flights and travels so far)
Sleep when the locals sleep.
That sounds really simple, and it is for the most part, and there are some exceptions for this tip. Lets use a trip to Paris from Boston as an example. if my flight to Paris leaves at 11pm, and Paris is 6 hours ahead, that means that it is 5am in Paris. Now I don't know about the Parisians, but personally at 5am I would be getting up and ready for my day, so this is a flight that I would not sleep on. So you hop on your plane, watch a few movies, and you land in Paris at noon (just to make things easy). Obviously you still have until at least 9pm til you will be sleeping. While most people would recommend a quick cat nap, I recommend a coffee, or something with caffeine, and to just power through it until its time to sleep. After all there is so much to do and see. Now on the way home from Paris, just don't sleep. The great thing about flying from Paris to Boston is the flight would take off at 10am and land around noon. While you would still have been up much longer, it is a much shorter time than when you were up all day at the airport heading to Paris, on a plane, and then powering through your first day of vacation. So don't sleep, power through it, and get some laundry done when you get home, then head off to bed a little earlier than you normally would, and you should be fine.
Now lets talk about long flights. I apparently thought that after traveling to Greece, which had the longest flights I had been on at a little over 9 hours, that flying to Thailand would be a breeze. That was until the tour company booked a direct flight from Boston to Hong Kong, that would then go to Bangkok. That initial flight is a cool 15 to 17 hours depending on path, weather, etc. (My flight was about 16 hours). Now I was also flying into somewhere that was exactly 12 hours ahead of Boston, at the final destination. For this flight I began preparing 24 hours before my flight would leave the US. I began sleeping or trying to sleep based off the time it was in Thailand. I would then continue this on the flight, and then when I landed in Hong Kong and traveled to Bangkok I would stay awake, as I was arriving around noon local time. Then I would have to power through the day and after falling asleep that night when the locals would, I was well rested, and my internal clock was reset. I was shocked that my crazy idea worked, but it did. So at the time that was all that mattered. Now for my fight home, I had the same as on my way there, just reversed. This meant though that I should sleep on my first flight, that was three hours, as everyone at home would be sleeping, and then on the 16 hour flight from Hong Kong to Boston I would have to stay asleep. This was especially important since I would be arriving in Boston just after midnight, so I would want to be able to fall asleep right when I got home.
Once again, this crazy idea seemed to work, and after sleeping until about 9am the next day, I was off to work by noon the day after my long flight. While these tricks might not work for everyone, these were huge for me on my recent travels to Thailand, Greece, and around Europe last winter. So I recommend considering this tip, as well as others that you can find online to see what might help you enjoy your vacation, and your arrival back at home just a little more, because no one wants to suffer jet lag.