Traveling Through Time Zonesby Eli Hendel, M.D. Medical Reviewer
Imagine the following scenario: You are traveling from New York to Paris. You have an important business presentation early the next morning and you want to make sure that you will be wide awake, energetic and fully functional. The time difference in Paris is 8 hours later than New York, so you know you’ll want to avoid what is commonly called jet lag. But what exactly is it?
Jet lag is caused by misalignment between the internal circadian clock (in your body) and the external environment. The net result is that you feel sluggish and weary.
When you travel and there is more than a three hour difference in the time zone of origin to the time zone of destination, you can experience symptoms of jet lag. Symptoms typically include: fatigue, headaches, and irritability. Symptoms that are specific to sleep include: trouble falling asleep if flying east, and early awakening if flying west.
What is this internal clock?The internal clock is located in a part of the brain called the hypothalamus. Through a very complex mechanism involving signals to many other parts of the brain, it alternates sleep and wakefulness through two specific hormones: Orexin which keeps us awake, and melatonin which stabilizes sleep.
At the end of the wakeful period of the day, when our brain is exhausted, there is accumulation of substances that basically send a signal of tiredness. That’s when melatonin takes over. Melatonin is typically secreted at night, so any exposure to light can suppress levels of the hormone. That is why it’s not a good idea to have the TV or reading light on when you’re trying to fall asleep.
Adjusting both your sleep schedule and sleep environment when traveling can help you avoid disruption to your body’s internal clock and sleep/wake cycle.
Preparing to Avoid Jet Lag When Going EastIf you are traveling eastward, then your body clock has to be advanced. Starting three days before travel, move your sleep period one hour earlier each day. You can accomplish that by getting exposure to bright lights for one hour upon waking up. Remember, melatonin gets suppressed by light. You can also help the process by taking melatonin tablets 5 hours before your usual bedtime.
Why is “five hours before sleep” the best time to take melatonin? To start, Melatonin is not a sleeping pill. The purpose of the melatonin supplement is to cause an earlier rise in the level of the hormone (artificially) so you “advance” your body clock. Normally melatonin starts to rise about two hours before your usual bedtime.. We call this phenomenon “Dim Light Melatonin Onset” or DMLO. By taking melatonin supplements, you’ll nudge the rise in levels so that DMLO occurs earlier, causing you to want to go to bed earlier.
Upon arrival at your new destination, avoid light in the morning (wear dark glasses or stay indoors) and then seek bright light outdoors in the afternoon. To further help to get adjusted to the new time zone, it’s alright to take a short nap, no longer than 30 minutes, during the mid-day.
Preparing to Avoid Jet Lag When Going WestIf your trip will take you westwards then you will be a bit less challenged because it’s actually easier to adjust to the western time change. Preparation basically involves delaying your usual sleep schedule. It’s also the exact opposite of the recommendations I described for eastward travel. Your three day preparation involves
avoiding light in early morning
staying indoors or wearing dark glasses during the day
seeking some light in the evening
The overall intent is to delay your sleep time by one hour each day, starting three days before traveling.
Whether traveling eastward or westward, caffeine should be avoided close to bedtime. The effects of caffeine can last up to 5 hours.
Preserving Sleep Hygiene
The basic guidelines offered here are to help you to maintain what is known as sleep hygiene. When preparing to take a trip to a faraway place, it’s very important to respect the difference between night and day, literally. You should avoid doing activities at night that keep you awake, especially those that involve light exposure. Watching TV or reading with a Kindle, common activities in bed that expose you to light, are enough to suppress your internal melatonin secretion and interfere with or change your internal clock.
One afterthought - Good health habits, like keeping a proper sleep-wake schedule, might also lead to (heaven forbid),healthier eating habits The timing of your meals should be in direct concert with the circadian rhythm which, in turn, that should be coordinated with the sleep-wake schedule. That of course is a whole other discussion…