Jet Lag: Causes, Symptoms, and Treatments

When we travel across time zones, we often experience jet lag, a disruption to our natural sleep-wake cycle. We each have an internal clock, also known as our circadian rhythm, that controls the times of day we feel awake versus tired. Our natural circadian clock is synced with the rising and setting of the sun. This cycle adjusts our body temperature, blood pressure, and hormone levels to influence sleep.

When traveling to a new time zone, our internal clock remains synced to our local time, rather than the new one. This causes a biological imbalance that affects our sleep and overall health.

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Throughout this article, we cover the causes and symptoms of jet lag. We also break down several different treatment options and ways to reset your internal clock.

Causes of Jet Lag

Disruptions to Natural Circadian Rhythm and Light Exposure

As we mentioned above, our circadian rhythm influences our sleep-wake cycle. This cycle is influenced by light. Receptors in the suprachiasmatic nucleus (SCN) receive light signals from the retina and set the circadian pacemaker to the correct time.

One of the key outputs of the SCN is the regulation of melatonin production by the pineal gland. During the day, melatonin production is low, In the evening, as light exposure decreases, melatonin increases, telling the body that it is night-time.

“Melatonin production is under circadian control as well as regulated by light. That means that the rhythm of melatonin production would be low in the day EVEN in complete darkness (circadian means it is generated by an internal biological clock),” explains Professor Professor Stuart Peirson at the University of Oxford.

We experience jet lag when our circadian rhythm becomes disrupted due to a change in time zone and light exposure. Jet lag symptoms worsen based on the number of time zones we travel across. Traveling to a location with a 1 to 3 hour time change may not cause perceptible jet lag. In other words, it will have effects, but many can shrug them off easily enough as a slight change in schedule.

However, traveling overseas to a time zone 6 to 12 hours different from your local time can cause severe jet lag. This is because your sleep schedule and other biological functions, such as hunger, are completely out of sync with the new time zone.

“Any shift in time zone can lead to resynchronization by shifting the clock forward or backward,” says Professor Peirson.

Symptoms have also been shown to worsen when traveling east rather than west. This is likely because it is harder to advance our internal clock than it is to delay it.

“As a simple rule, for every 1h time zone difference your body will need 1 day to re-adjust,” says Professor Peirson. “So, if you travel across 6 time zones, you will only finally be adapted to the new local time after 6 days. If this is for a week’s trip, this is just as you are getting ready to go home, which is perhaps why people find jet-lag so frustrating.”

Airplane Cabin Pressure and Atmosphere

Studies show symptoms of jet lag are also influenced by the high altitudes and low oxygen levels associated with air travel. When less oxygen reaches the brain, it causes lethargy and symptoms similar to altitude sickness, such as fatigue, nausea, and headaches. The low humidity levels inside the airplane cabin can also cause dehydration and make jet lag even worse.

Travel Fatigue

Frequent travelers, such as flight attendants and business travelers, often develop travel fatigue. Travel fatigue is not always connected to jet lag. However, the total exhaustion and stress associated with constant travel cause symptoms similar to jet lag, such as daytime fatigue, mood swings, and the inability to focus.

Symptoms of Jet Lag

The symptoms of jet lag can vary based on the number of time zones crossed, your age, and overall health. Older adults and those with medical conditions typically experience more severe jet lag symptoms and often need more time to become synced to a new schedule.

• Daytime sleepiness, fatigue, and low energy levels
• Sleep disturbances, including insomnia, oversleeping, and frequently sleep disruptions
• Poor cognitive function and difficulty focusing
• Headaches and dizziness
• Slow hand-eye coordination
• Mood swings
• Digestive issues, such as nausea
• Loss of appetite

Treatment for Jet Lag

In most cases, jet lag is temporary. Once your body clock becomes synced to your new time zone, you will start sleeping regularly and experience fewer nighttime disruptions. However, there are preventative measures that can speed up the adjustment process and decrease symptoms.

Manage Light Exposure

The best way to treat jet lag is by resetting your body’s internal clock—this can be done by naturally influencing your circadian rhythms and melatonin production with light exposure. When you are ready to sleep, whether on the plane or hotel room, make sure your sleep space is as dark as possible. You can do this by using an eye mask or closing the blinds and curtains in your room. This will prevent inappropriate light exposure.

If you arrive at your new location in the morning or afternoon but plan to sleep right away, wear sunglasses when leaving the airport to prevent too much sunlight exposure.

If you plan to stay awake once you arrive, increase your sunlight exposure by sitting or walking outside during the daylight hours. More sunlight naturally shifts your circadian rhythms to the new time zone and also has an alerting effect to help you feel awake.

Timing of Flights

When purchasing your flight, try to arrive at your new location in the morning or early evening. Arriving in the morning allows you to sleep on the plane and begin your day once you arrive. If you arrive in the early evening, you can plan to sleep around 10 p.m. local time. Therefore, you will be more in sync with the local bedtime.

If you have a meeting or an important event, try to arrive in your new time zone 2 to 3 days in advance. This extra time gives your biological clock plenty of time to adjust first.

“When you sleep is determined by your circadian clock and by how long you have been awake. As such, if you have been awake for a long time, you will still be able to sleep at the wrong circadian time. Conversely, if you have slept in and haven’t been awake for long, even sleeping at the right circadian time can be difficult. As a result, a routine really helps your body adjust” says Professor Peirson.

Gradually Adjust Your Sleep Schedule

Before you leave your local time zone, you can gradually adjust your sleep schedule to your new time zone. If you are traveling east, start by going to bed 1 hour earlier than you normally would. Gradually increase your bedtime by 1 hour for 3 to 4 nights before departure. If you are traveling west, go to bed 1 hour later every night. Delay your sleep each night for roughly 3 to 4 nights.

“This doesn’t have to be militant,” notes Professor Peirson. “A subtle shift in the right direction can help. Shifting mealtimes in the direction of your destination time zone may help too.”

Physical Activity

If you plan to arrive at your new location in the afternoon or evening, you should stay awake on your flight. This can make it easier for you to fall asleep once you arrive. Gentle stretching and walking on the plane improves blood circulation and keeps your body and mind alert. Likewise, once you land, exercise can help you stay awake until bedtime.

Sync to the Local Schedule

Once you arrive, try to sync to your new time zone. This includes your sleep schedule and mealtimes. By immediately adjusting your schedule, you help your body’s internal clock sync to the new time zone.

Stay Hydrated and Eat Light

On long flights, be sure to drink plenty of water. Staying hydrated prevents dehydration and reduces symptoms of jet lag. Also, be sure to eat light and healthy snacks and meals. When your body is working to digest heavy, fatty foods, it can be difficult to fall asleep and rest soundly.

Conclusion

Although jet lag is inconvenient and uncomfortable, the tips outlined above can help reduce symptoms and get your sleep schedule back on track. When traveling to different time zones, especially those drastically different from your local time, it is essential to take care of your body. A healthy diet, plenty of water, regular physical activity, and controlling your natural melatonin production will help you adjust to your new location quickly.