One of the design flaws of being human is not being able to cope with crossing the globe in a single day. Granted, that's hardly been an issue for our entire existence until recently when airplanes were invented. The fastest our ancient ancestors likely traveled was at the breakneck speed of a runaway horse, and they experienced nothing more annoying than leg cramps after long distances. Even traveling by ship would have allowed your body a chance to cope with changing time zones. However, since we have learned how to launch people up in the air and hurtle them through the clouds at hundreds of miles an hour, we have equally learned that our physiology will have a few hiccups. For that reason, I'd like to put a suggestion in the suggestion box for our next evolutionary upgrade - the ability to adapt to rapidly changing time zones. But until humans evolve in that very convenient direction, we must find ways to minimize its effect to hit the ground running.
Two unfortunate things happen when we take long-haul flights, and we can't blame "jet lag" on everything. First, we experience the humble "travel fatigue," where the travel experience wears you out, and general fatigue sets in. We become slightly dehydrated and may experience some headaches. According to an article on Frontiers in Physiology, these niggling travel fatigue symptoms are caused by sleep loss, dehydration, hypoxia (diminished oxygen levels), and discomfort resulting from the aircraft's confined spaces, low air pressure, and humidity.
Jet lag, on the other hand, can be described as a mismatch of someone's daily biological rhythms and time zone, according to the CDC, but it's a little more intricate than just being a little sleepy. Our bodies are hardwired to keep a schedule known as our circadian rhythm (our 24-hour schedule that regulates our alertness). If you've ever experienced jet lag, you'll have felt the effects of ripping up the plan. It feels like you're powering down when you should be powering up, and you're "tired and wired" at night when you should be sleeping. However, other processes other than our awake/sleep schedule can be affected. Hormone release, melatonin, temperature control, and digestion are perfectly timed to keep you alert during the day and power down appropriately when the sun starts to set. A disruption in our schedule can lead to symptoms like headache, irritability, daytime sleepiness, difficulty sleeping at night, poor mental and physical performance, and poor gastrointestinal function. For women, it may include disruptions in our hormonally driven menstrual cycles.
The reason for this mass disruption is that every cell in our body is linked to a master biological clock, as the National Institute of General Medical Sciences puts it. This master clock connects over 20,000 nerve cells, forming a suprachiasmatic nucleus (SCN) structure. This master clock drives every process in our bodies; nearly every cell and organ is involved, from when to release our hormones to our hunger and digestion to even our body heat regulation. Our SCN receives input on the time of day through a timekeeper or a timing cue called a "zeitgeber," which are cues in our environment that alert the body to whether or not we should sleep or be awake. One of the zeitgebers is sunlight, and our SCN takes direct input from our eyes. According to the article in Frontiers, Zeitgeber's can come from other cues such as social contact, eating, and physical activity.
When we fly into a new time zone, our natural circadian rhythm can't immediately process the new zeitgebers in the new time zone, and it takes a few days to get our feet back under us and operate at our best. The rule of thumb is that it takes one day of recovery for every time zone you cross. However, there are a few ways to improve how we feel in our new destination, just by altering a few simple food, sleep, and exercise habits at home.
Dr. Stacy Sims, who coaches international athletes who participate in global events, advises changing your bedtime and wake-up time a little bit each day before your flight. This helps your body slowly make the adjustments it needs. Instead of keeping the lights on until bedtime, which will alter when your melatonin levels drop, turn off the lights in your house and close the curtains so your home naturally falls dark with the natural sunset.
Melatonin is naturally released when the brain identifies it's dark outside to start our sleep cycle. According to Frontiers, taking melatonin in the late afternoon or early evening, before the natural melatonin release, will help shift your circadian rhythm to finish the day earlier. Likewise, pushing your melatonin intake until later can help push it forward.
According to the Sleep Foundation, tart cherries or tart cherry juice contain melatonin and tryptophan if you're not interested in taking a melatonin supplement. Tryptophan can encourage melatonin production.
When flying west to east, Dr. Stacy Sims recommends ingesting 4 ounces of tart cherry juice approximately 30 minutes before bed, then waking up one hour earlier than usual. Four days before your trip, drink 4 ounces of tart cherry juice (for natural melatonin) with 400 milligrams of valerian about 30 minutes before bed. Go to bed and wake up 1 hour earlier than usual. When you wake up, start the "wakeful" process by opening your curtains to bright sunlight or going outside.
Team USA takes jet lag seriously, sending their athletes worldwide and asking them to perform their best. One of their tactics for ensuring that their athletes hit the ground running, so to speak, is to change their meal intake times to reflect the time in the destination location. That means eating breakfast, lunch, and dinner in the destination time zone a few days before taking off.
If changing your meal schedule seems too cumbersome, focus on your coffee intake. Coffee has a half-life (where it remains in the bloodstream for approximately 5-6 hours post-drinking it) and can affect your sleep/wake cycles. The Human Kinetics Journal tells us that around 200 mg of caffeine has been shown to delay melatonin release when taken 3 hours before bedtime. Also, 300 mg of slow-release caffeine taken at 8 am (destination time) for five days “resulted in a more rapid resynchronization rate than placebo.”
Now that we know that jet lag isn't entirely responsible for feeling rubbish, and travel fatigue and dehydration are also culprits, focus on drinking enough water (approximately 8 ounces of fluid) every hour and eating high-water foods while traveling. Cucumber slices and watermelon are examples of high-water content food (also easy to pack). Team USA even suggests that you monitor your bathroom visits, aiming to drink and eat enough water-based foods for a bathroom visit every 2-3 hours.
Although sugary airport snacks look alluring and promise to make you more alert, you're better off skipping the sugar high to escape the inevitable sugar crash. These packaged, processed foods also can leave you feeling bloated and sluggish, so the temporary high isn't worth the inevitable low. The same goes for alcohol, which can dehydrate you and leave you feeling poorly when you land.
All of these tactics will kick-start your vacation in the best way possible.