Since so many people enjoyed my sleep tips, here's a bonus post on preventing jet lag. Jet lag happens when you travel across multiple time zones, because your circadian rhythms get out of phase with your sleep/wake cycle. Put more simply, your brain's internal clock is no longer synchronized to the clock on the wall. That discrepancy can either make it hard to fall asleep, or make you too sleepy when you're trying to stay awake, depending on the direction of travel and the time of day. For some people jet lag can also cause dizziness, indigestion, or a general uneasy feeling (perhaps some of your are feeling this way right now).
Interestingly, you don't even need to travel to give yourself jet lag. If you stay up partying every night for a three-day weekend, at work on Tuesday morning you might experience "social jet lag." This too is your clock getting out of synch with everything else. In fact some symptoms of a hangover may simply be desynchronized circadian rhythms. However, in this post I'll focus on the travel kind, and specifically how to prepare for travel in order to avoid the worst of it.
For a little background, your circadian rhythms are a collection of various hormones released at specific times throughout the day. These hormones control your alertness, sleepiness, mood, pain threshold, energy level, body temperature, and sex drive (and no I'm not sex-obsessed, it's just science). For example, if you go to sleep at midnight, your brain releases melatonin around 11:30PM and your body temperature drops to prepare for sleep. At around 4AM your body reaches its lowest temperature. Then to prepare for your day, your body releases cortisol, a stress hormone, around 6AM, and adrenaline a little later on. So when you travel East across the country and it's suddenly three hours later than it's supposed to be, you have to go to sleep with no melatonin to assist you. Or if you travel West and it's suddenly 3 hours earlier, your body is releasing cortisol and adrenaline while you're still trying to sleep.
The main clock that regulates these rhythms is kept in the suprachiasmatic nucleus of the hypothalamus, which sits just behind your eyes (about an inch in from where your unibrow used to). It keeps on ticking to make sure all the hormones get released at the right time. Interestingly it's not a 24-hour clock. For most people it's about 24 hours and 11 minutes (Side note: Some people have 24.5 hour clocks, and some are under 24, which may help explain why some people need more sleep, and others need less). Perhaps you can see a problem here. Since your clock is 24 hours and 11 minutes, but the world exists on a 24-hour day, if you lived at your natural rhythm you would release all your hormones 11 minutes later each day. By the end of the week you'd be showing up to work an hour later. By the end of the month you'd sleep in until the afternoon (maybe some of you do that anyway). In order to stay synchronized to the real world your clock needs to reset itself every day.
Here lies to key to easing jet lag. Your brain uses bright light through your eyes (ideally sunlight) to synchronize itself to the world. Hence the reason your brain's clock is located so close to your eyes. You can use this info to help you start synchronizing yourself to your new time zone, even before you leave. Interestingly, bright light also helps boost serotonin, which may not be unrelated, considering serotonin is a precursor to melatonin.
Unfortunately, the brain's clock is not fully flexible in it's ability to reset. It can only shift its time by about an hour forward, or 2 hours back, each day. It is exactly this reason that we get jet lag. For example, if you travel 3 time zones East, it will take about 3 days for your clock to fully adjust three hours ahead. The reason why it's easier to travel West than East is because it's easier to shift your clock back (i.e. delay release of melatonin), than to move it forward.
If you're traveling West you need to shift your clock back. For example, if you're going from New York to LA you need to shift it back by 3 hours. To do this, look at bright lights at night (turn on all the lights in your apartment, or go to Times Square). This tells your brain that the sun is still up, so it needs to delay release of melatonin. In addition, avoid bright lights in the morning, so your brain will think the sun hasn't risen yet. You will need to do this a couple days in a row to shift your clock. It is also helpful to exercise at night, which increases your body temperature and also shifts your clock backwards. If you're really serious about shifting though, you'll have to stay up late and sleep in. Sleeping in is the important part, because you need to get enough quality sleep. Sleeping in also helps avoid bright lights in the morning.
If you're traveling East, then you need to do the opposite. Avoid as much light as possible in the evening, go to sleep early, and get a lot of bright light when you wake up. It also helps to exercise right when you get up to increase your body temperature. There is some evidence that taking melatonin supplements 3-4 hours before your normal bedtime, will help advance your clock. Once you start traveling though, melatonin is more difficult to make use of. This is because the effect of melatonin changes depending on what time your brain is at. Because your brain's time will be changing once you travel, you might take the melatonin at the wrong time.
Perhaps most important to diminishing jet lag symptoms is to get enough quality sleep for the few days before your trip. When your brain is well rested it is more able to adjust to time changes. It's also helpful to avoid taking the red-eye, mainly because you'll be getting light at the wrong time and not enough quality sleep. Drinking plenty of water is also helpful, but just because many people get dehydrated while traveling.
Once you get to your destination use all the tips for good sleep hygiene. Get plenty of light in the morning and during the day, and avoid it at night. Don't exercise too close to bedtime, and don't take naps. If you're traveling farther, to Europe for example, it may be very hard to avoid taking naps, but tough cookies. Don't take a nap when you're trying to adjust your clock. If it's daytime where you are then stay active out in the sunshine.
Lastly, forget about what time it is in your "home" time zone. The more you think about what time it is where you came from, the more difficult it will be to adjust psychologically. You will adjust fastest to your new time zone if you just focus on the time where you are.
I know jet lag is annoying, and it would be ideal if we could just shift our clock immediately to the new time zone. Unfortunately we didn't evolve with high-speed jet travel. We can only adapt so much from the way our brains evolved to work (shout out to my homies in evolutionary biology ... keep it real). If the symptoms of jet lag are just too much, try jogging to your destination, and then you won't get any jet lag at all.