Can You Decrease Jet Lag With Exposure to Light?

By Dr. Mercola

Your body is designed to run on a 24-hour cycle, or circadian rhythm. Many things can throw this delicate cycle off, however, including traveling across multiple time zones. When there’s a disconnect between what time your body thinks it should be, and what the actual local time is, the resulting condition is known as jet lag, and it affects most air travelers who cross five or more time zones.¹

It’s typically worse when traveling eastward than westward, which is because your body’s internal clock actually runs on a slightly longer than 24-hour schedule. When you travel to the west, the day gets longer, which is easier for your system to handle than traveling east, which means the day gets shorter.²

Light cues from the environment also play a major role in jet lag symptoms. Inside the suprachiasmatic nucleus (SCN) of your brain, which is part of your hypothalamus, resides your master biological clock. Based on signals of light and darkness, your SCN tells your pineal gland when it’s time to secrete melatonin — promoting sleep — and when to turn it off.

This is why light therapy has been revealed as one of the most promising tools for treating jet lag. Light exposure at the correct times can help to synchronize your body’s clock with the environment around it.

Cheat Sheet to Use Light Exposure to Fight Jet Lag

Exposure to light leads to advances or delays in your circadian rhythm, known as phase shifts, which can cause the symptoms of jet lag to disappear. Typically, exposure to light early in the morning causes a phase advance, which leads to earlier waking. Light exposure at bedtime will lead to a phase delay, or later wakening. Researchers explain in the journal Sleep Medicine Clinics:³

“Flying east requires a phase advance of the circadian clock, and flying west requires a phase delay. For example, when it is early in the day in the U.S., it may already be approaching nighttime in Europe. Common language for those in the U.S. is to say that Europe is ahead of us, and when you arrive there you have to set your wristwatch ahead by moving the hands later.

However, your circadian clock has to be reset earlier, and the technical term is a phase advance. For example, if you flew east seven time zones (e.g., Chicago to Paris) and expect to go to sleep at midnight in Paris, you are really trying to go to sleep at 5 p.m. according to the time of your circadian clock, which is still on Chicago time.

You are trying to go to sleep earlier, to advance the time of your sleep, and your internal circadian clock has to phase advance to realign with your advanced sleep schedule and the new local time.”

When traveling east, exposure to bright light in the morning, and the avoidance of bright light at night, should help to minimize jet lag, while the opposite holds true when traveling west.

However, it gets complicated when you travel through six or more time zones, which, as pointed out by Dr. Michael Greger, a nutrition expert, physician and founder of NutritionFacts.org, may confuse your body clock, causing it to adjust in the wrong direction. He offers the following cheat sheet to remember if you’ll be embarking on long-distance travel:⁴

“[I]f you fly from LA to London, eight time zones east, you’d avoid light between 6 a.m. and noon local time, and expose yourself to light between noon and 6 p.m. local, and the rest of the day, it doesn’t matter and won’t affect you either way …

On subsequent days, the local times of light avoidance and exposure need to be advanced [earlier] by [one to two hours] each day, until light avoidance coincides with [when you’re sleeping].”

If you need to avoid light exposure in the morning, consider wearing a pair of blue light-blocking glasses with amber lenses, which will help to prevent your melatonin levels from plummeting (this can’t be achieved via regular sunglasses). Blocking blue light is known to help regulate your internal clock to control sleep patterns.

Light Therapy May Relieve Jet Lag Symptoms

Disturbed sleep, including insomnia, early waking or daytime fatigue, is the hallmark of jet lag, but it can also cause additional symptoms ranging from grogginess and difficulty concentrating to mood changes and stomach problems.

Research is promising, though, that light exposure may offer a solution, especially when combined with carefully timed melatonin supplements. According to one paper published in the Journal of Molecular Microbiology and Biotechnology:⁵

“Critically timed exposure to bright light and melatonin administration can help to reduce symptoms. Bright light is one of the most powerful synchronizers of human rhythms and melatonin serves as a ‘dark pulse’ helping to induce nighttime behaviors.

Thus, enhancing day and night signals to the brain, appropriate to the environmental light/dark cycle of the new time zone, can serve to re-establish adaptive timing relationships between the body’s internal biological rhythms and the external environment, and thereby reduce the symptoms of jet lag.”

You can achieve bright light exposure by going outdoors into the sunlight, using a light box or using a device that offers transcranial bright light (TBL) via your ear canals. TBL has previously been shown to have antidepressant and antianxiety effects, and it may also enhance psychomotor performance.

When researchers administered TBL for 12 minutes, four times a day, in the seven days following an eastward transatlantic flight, it led to a significant reduction in jet lag symptoms, sleepiness, fatigue and forgetfulness. The results were cumulative, emerging three to four days after travel, with researchers concluding, “Intermittent TBL seems to alleviate jet lag symptoms.”⁶

Even light therapy that exposes people to short flashes of light while they sleep may be beneficial, not to mention convenient (perhaps even being administered prior to your trip, while you sleep). What’s more, being exposed to short two-millisecond light flashes every 10 seconds for an hour worked better than continuous light exposure for an hour.⁷

The flashes led to two hours of adjustment in circadian rhythm, compared to 36 minutes from the continuous exposure.⁸ You can also use outdoor light to manipulate the symptoms of jet lag.

“After a westward flight, it is worth staying awake while it is daylight at the destination and trying to sleep when it gets dark. After an eastward flight, one should stay awake but avoid bright light in the morning, and be outdoors as much as possible in the afternoon,” researchers wrote in BMJ Clinical Evidence. “This will help to adjust the body clock and turn on the body’s own melatonin secretion at the right time.”⁹

Using Melatonin to Avoid and Relieve Jet Lag

In cases when you need to phase advance your circadian clock (leading to earlier waking), exposure to intermittent bright light in the morning along with melatonin supplementation in the afternoon and gradually advancing your sleep schedule have been found to be effective.¹⁰ You might consider this option prior to eastward jet travel.

If you’re traveling at night, wear blue-blocking glasses on the plane and continue wearing them until you go to sleep, as excess blue light will impair your melatonin production and make it difficult to fall asleep.

Also, once you’re at your destination, get up as close to sunrise as possible and go outside. This will help to reset your melatonin production. If weather and circumstances allow, it would be best to do this outdoors with your bare feet on the ground.

Then, just before bedtime, take a fast-acting sublingual melatonin along with a slow-release oral melatonin. Keep in mind that only a very small dose is required — typically 0.25 mg or 0.5 milligrams to start with, and you can adjust it up from there. Taking higher doses, such as 3 mg, can sometimes make you more wakeful instead of sleepier, so adjust your dose carefully.

According to a 2002 Cochrane Database review, people who traveled across five or more time zones and took melatonin close to bedtime at their destination experienced less severe jet lag symptoms compared to placebo.¹¹

You can also get some melatonin via your diet. If you prefer to use food, pistachios are the most melatonin-rich nut, and can provide measurable amounts in just two nuts. Eating a small handful of them before bed could give you a meaningful melatonin boost.

Keep in mind the release of melatonin is dependent on the release of another hormone, norepinephrine. Excess stress, and the resulting release of cortisol, will inhibit the release of norepinephrine and therefore the release of melatonin.¹² So consider engaging in stress-reducing strategies before bed, such as yoga, stretching, meditation and prayer.

Sleeping in complete darkness is also important. If you get up during the night to use the bathroom, be sure to keep the lights (and night lights) off so you don’t shut off your production of melatonin.

Magnesium also plays a role in reducing brain activity at night, helping you to relax and fall asleep more easily. It works in tandem with melatonin. Foods containing higher levels of magnesium include almonds, avocados, pumpkin seeds and green leafy vegetables.¹³

More Tips for Avoiding Jet Lag

The stimulation of certain acupuncture meridians is sometimes used in Traditional Chinese Medicine (TCM) as a technique for alleviating jet lag. One simple version of this technique is demonstrated in the video above (originally taped in 2009) by cardiologist Dr. Lee Cowden, using your heart meridian. Here’s a summary of the steps:

Also, when adjusting to a new time zone, be sure to shift your mealtimes accordingly. You can do this once you reach your destination or start prior to your trip. Another strategy, developed by researchers at Harvard and Beth Israel Deaconess Medical Center in Boston, is called the anti-jet lag fast.

It involves determining the time of breakfast at your destination and then fasting for 12 to 16 hours beforehand. This strategy is thought to work because fasting causes your master clock to suspend the circadian clock and instructs your body to sleep less. When food intake resumes, the master clock switches the circadian clock back “on.”¹⁴

Combining these dietary and TCM strategies along with properly timed light exposure and melatonin are likely among the best ways to relieve jet lag symptoms so you can start your trip off right.

If you have an upcoming flight scheduled, Jay Olson, Ph.D., created Jet Lag Rooster,¹⁵ an online calculator that lets you input your flight time and destination, along with your usual sleep and wake times. It then gives you a customized plan to best reduce jet lag using light exposure and, optionally, melatonin.

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