Traveling by air across several time zones will result in jet lag. The human body has a circadian rhythm that is based largely on a 24-hour cycle. Every 24 hours, the body does a number of things on schedule, far exceeding simply going to sleep and waking up. For example, melatonin is produced in the evening and helps a person fall asleep. Cortisol is the opposite, and is produced in the morning to stimulate waking (among other things). Body temperature and blood pressure fluctuate on a daily basis, both reaching a low point about two hours before waking. This cycle, according research done with people who were allowed to sleep and wake according to their own body system, is about 24 hours and one minute, give or take 16 minutes, depending on the person. But, since the body resets its clock every day, according to the sun, people are able to stay on track.
When traveling east or west, the body is forced to operate on a cycle that no longer equals 24 hours in a day. The human body can usually adjust about one hour per 24 hour period, and still feel normal. Any more than this, and the circadian rhythm is too out of sync with the daily light and dark period, and the person experiences jet lag.
Jet travel can produce up to a twelve hour time difference from the home time zone. While people sometimes talk about experiencing a 15 hour time difference (based on clocks and calendars), such as between the United States and east Asia or Australia, this would only be a nine hour difference based on the rotation of the earth. Since the human body doesn’t take clocks or calendars into account, and bases its internal rhythm solely on the light and dark periods every day, twelve hours is the max difference. This means that left to its own devices, the body can take up to twelve days to adjust to the new time difference. This is fine for people on a cruise in the Bahamas, or who are moving to a new country long-term, but for vacationers, adjusting to jet lag quickly is important.
To adjust quickly to jet lag, a bit of mental and physical preparation is important. Before the trip, get as much sleep as possible. This method of hacking the system will be hard, pre-trip sleep deprivation may make it impossible. In the week or so leading up to the trip, take naps, go to bed early, and sleep in if possible. The timing doesn’t matter in the slightest, since you’ll be changing when you sleep anyway.
After getting on the plane, set your watch to the time zone of the final destination. Planes have a non-standard time schedule, so it doesn’t do any good to keep track of departure time zone – it’s no longer relevant, and the plane won’t use it anyway. Forget it. The destination time is the right time. On the plane, feel free to take nap or two, or stay awake. You won’t get a full night’s rest even if you sleep, since airplane seats aren’t very comfortable, but it might give you a bit of an edge for the next phase of the adjustment plan.
Upon arrival, you mission is now to stay awake until dark. It’s easiest to accomplish this when your flight arrives in the afternoon, but regardless of the time your feet touch down in the new country, don’t allow yourself to fall asleep while the sun shines that first day. Depending on the time difference, this may mean that you’ll be awake for 30 hours or so (not counting little naps on the plane), so the urge to sleep will be incredible. Just sitting down to “rest your eyes” for a few minutes will turn into a multi-hour nap, so don’t let this happen. Go for a walk, and stay physically active that first day.
If weather permits, watch the sunset. This will help your body understand that the day is ending. Once it is dark, feel free to sleep. It will be the middle of the day according to your circadian rhythm (which is still on home country time), but being awake for so long will mean that you’ll have no trouble falling asleep. Ideally, this exhausted sleep will last for several hours, and when you wake up, it will be early morning. The second day, do not take naps. It will be hard again, but probably not as hard as the first day (since you’ll only be up for about 15 hours instead of 30). By day three, your body will likely be nearly completely adjusted.
Keep in mind that naps the first week will make the adjusting process take longer. Watching the sun come up and go down will make the process go shorter, as these are the primary method the body uses for determining what time it should be.
By Andy Summers