Jet Lag Disorder

About Jet Lag Disorder

Jet lag occurs when your internal body clock, or circadian rhythm, is disrupted when you travel across multiple time zones and your internal circadian clock no longer matches the local time. The circadian rhythm regulates sleep-wake cycles and other biological processes. The circadian rhythm is synchronised with environmental cues, specifically daylight and darkness, to promote normal function and your physical and mental health. If you travel across multiple time zones (typically three or more), your circadian rhythm struggles to adjust to the new schedule and may not reset to the new time zone and the new light-dark cycle quickly enough, leading to symptoms of jet lag. The symptoms of jet lag can last for days or weeks.

The severity and duration of jet lag symptoms can vary among individuals and can be dependent on multiple factors, including:

The number of time zones crossed.
The direction of travel (eastward or westward).
Individual susceptibility.
Pre-existing sleep disorders.
Pre-existing medical conditions.

While travelling long distances can already take a mental and physical toll, travelling long distances across multiple time zones can add to the physiological and emotional stress further.

Jet lag most commonly affects travellers who fly long distances, particularly eastward or westward, where the time difference between the origin and destination is significant. Your internal circadian clock typically takes between 1 and 1.5 days to adapt to each time zone you cross. For example, if you fly from London to Singapore, you will travel through seven time zones, meaning it could take between 7 and 10.5 days for your circadian rhythm to adapt and you may experience jet lag for the duration of this time. However, there are things you can do to help your circadian clock and prevent or minimise the effects of jet lag.

Understanding jet lag and how to prevent or minimise it can cause fewer disruptions to your circadian rhythm and your sleep and can result in fewer or shorter-lasting symptoms.

Research has shown that jet lag is worse when travelling east, compared to travelling west. When you travel west, the time zones go back (for example, 6 pm in London is 1 pm in New York). This means you ‘gain’ time and prolong the circadian rhythm’s normal day-night cycle. Recovery from jet lag typically occurs faster when travelling westward compared to eastward.

Jet lag does not usually occur when travelling north or south within the same time zone. For example, if you fly from Edinburgh to Timbuktu, although you may feel extreme tiredness and other adverse symptoms from the long flight time, because you have travelled within the same time zone, you will not be experiencing jet lag. Instead, you will likely be experiencing travel fatigue. Some of the symptoms of travel fatigue are similar to jet lag, such as tiredness and headaches. However, travel fatigue is not related to disruptions to the circadian rhythm and is instead related to the physical and mental stress of travel. Travel fatigue usually goes away after sleep.

Causes and Risk Factors

Usually, the more time zones you cross, the worse your jet lag will be. Jet lag occurs when the body’s circadian rhythm is disrupted. The circadian rhythm is (approximately) a 24-hour cycle and is essential for regulating the timing of a variety of physiological processes throughout the day, including temperature, hormone secretion, digestion, heart rate, blood pressure and brain activity. For example, body temperature typically follows a circadian pattern, peaking in the late afternoon or early evening and reaching its lowest point during the early morning hours before rising again. The circadian rhythm is primarily synchronised with the external environment, particularly the cycle of daylight and darkness, through a complex interaction of brain chemicals or neurotransmitters, most specifically, melatonin.

Also known as the sleep hormone, melatonin is produced by the pineal gland in response to darkness and sends a signal to the body that it is time to sleep. The production of melatonin increases in the evening and peaks during the night, creating feelings of sleepiness. Exposure to light, especially natural sunlight, suppresses the production of melatonin and sends a signal to the body to wake up.

Not everyone who travels across time zones gets jet lag and some people get it much worse than others. Multiple factors can influence the occurrence and severity of jet lag, including:

The number of time zones crossed – The more time zones you cross and the greater the difference between the departure and destination time zones, the more severe your jet lag is likely to be. Crossing multiple time zones can disrupt the body’s internal clock more significantly, leading to more severe symptoms.
Direction of travel – The direction of travel—whether eastward or westward—can affect the intensity of jet lag symptoms. Generally, travelling east tends to result in more severe jet lag because it requires the body to adjust to a shorter day, while westward travel may lead to milder symptoms as it extends the day.
Individual susceptibility – Individual people react differently to jet lag based on factors such as age, overall health, pre-existing sleep disorders and genetic predisposition. Older adults, for example, may experience more difficulties adjusting to new time zones compared to younger people.
Pre-travel sleep quality – The quality of sleep in the days leading up to travel can influence how well the body copes with jet lag. Poor sleep hygiene or sleep deprivation prior to departure can result in more severe symptoms upon arrival at the destination.
Flight conditions – The conditions during the flight, such as cabin pressure, humidity levels and comfort, can affect how well individuals rest during travel. Long flights with uncomfortable seating arrangements or disruptions may contribute to increased fatigue and worse jet lag symptoms.
Pre-existing health conditions – Individuals with underlying health conditions, such as sleep disorders, anxiety or gastrointestinal issues, may experience heightened jet lag symptoms. These conditions can interact with the effects of jet lag, making it more difficult to cope with any disruptions to the body’s internal clock.
Stress and anxiety -The stress and anxiety associated with travel, particularly long-distance travel or unfamiliar destinations, can exacerbate jet lag symptoms. High levels of stress hormones in the body can disrupt sleep patterns and result in increased fatigue and irritability.

Travel schedule and duration

The timing and duration of travel can also impact jet lag. There are many factors connected to your trip that can worsen symptoms of jet lag, including:

The length of the flight.
Whether you are flying in the day or at night.
Whether you have any stopovers.
Your arrival time.
The length of your trip.
Your planned activities during your trip.

Additionally, frequent travellers who regularly cross time zones may experience chronic jet lag, leading to ongoing, long-term symptoms.

Symptoms of Jet Lag

Jet lag can affect different people in different ways, with some people experiencing more severe symptoms than others. Some of the most common symptoms of jet lag include:

Sleeping difficulties – Jet lag can lead to short-term insomnia, including difficulties falling asleep or staying asleep during the night. You may also wake up much earlier than planned or your sleep may be broken.
Fatigue – You may feel tired or exhausted, regardless of how much sleep you had the previous night. You may also find that your energy levels are low.
Daytime sleepiness – You may feel drowsy or lethargic during waking hours.
Difficulties concentrating – Many people with jet lag experience impaired thinking. You may have difficulties focusing, thinking clearly or performing cognitive tasks. You may also have difficulties with your attention or your memory. Mental fog and decreased alertness are common symptoms of jet lag and can affect performance at work or school.
Irritability – The disruption of sleep patterns and physical discomfort associated with jet lag can lead to irritability, mood swings and heightened emotional sensitivity. You may experience increased sensitivity to stressors and changes in mood, which can lead to irritability and sudden negative emotions. For example, you may be more likely to become angry or upset. Relationships and interactions with others may be strained as a result.
Mental health difficulties – Some people with jet lag experience emotional or mental health difficulties. Because jet lag can exacerbate existing mental health difficulties, people with existing or previous mental health conditions, such as depression or anxiety, may experience more extreme symptoms.
Gastrointestinal disturbances – Digestive issues such as indigestion, bloating, abdominal discomfort or changes in bowel habits are common when changing time zones.
Appetite changes – Some people experience a loss of appetite, increased appetite or increased cravings for specific foods.
Headaches – Mild to moderate headaches or migraines may occur due to disruptions in sleep patterns and dehydration.
Decreased physical function – For some people, jet lag can cause their body to feel tired and can affect physical performance.
Muscle soreness – This can include aching muscles or general feelings of physical discomfort.

Coping Strategies and Mitigation

There are multiple strategies you can implement before, during and after your flight to help reduce the effects of jet lag.

Before the flight

Gradually adjust your sleep schedule in the days leading up to the trip to better align with the time zone of your destination.
Get quality sleep in the lead-up to your flight.
Stay hydrated in the lead-up to your flight (dehydration can exacerbate the symptoms of jet lag).
Plan your trip to arrive a few days before any events or meetings.
Minimise your travel stress, for example, by packing in advance and giving yourself plenty of time to get to the airport.

During the flight

Avoid or limit your consumption of caffeine.
Avoid or limit your consumption of alcoholic drinks.
Drink plenty of water and ensure you stay hydrated. Keep in mind that flying can dehydrate you so you may need to drink more water than usual.
Eat smaller meals more frequently and opt for healthier food, such as fruit and vegetables.
Stretch and walk around the cabin, where possible.
Choose loose, comfortable clothing for the flight.
If the flight coincides with nighttime at your destination, try to sleep.
Wear earplugs and an eye mask and use a comfortable pillow to encourage sleep.

After the flight

Expose yourself to natural sunlight to help regulate your circadian rhythm.
Reduce your light exposure if you land at night, for example, by dimming indoor lights, wearing sunglasses indoors or avoiding using electronic devices.
Engage in light physical activity, such as walking or stretching. Exercise is especially beneficial if done outside.
Avoid daytime naps or only take short naps that are at least 8 hours before your bedtime.
Change your sleep schedule to the new time zone as soon as possible, for example, avoid sleeping during the day and set an alarm to avoid sleeping in too late in the morning.

Resetting the Internal Clock

Once you have arrived at your destination, your internal body clock will likely be out of sync with the new time zone. Adjusting to the new time zone and resetting your internal clock can be difficult, particularly because different bodily processes adjust to the new time zone at different rates. Resetting your internal clock is necessary for minimising the symptoms of jet lag symptoms and helping you to adapt to the new time zone.

To help encourage your internal body clock to reset more quickly, you can:

Gradually adjust your sleep schedule

Before travel: In the days leading up to your trip, gradually adjust your sleep schedule to better align with the time zone of your destination. If you’re travelling eastward, try going to bed and waking up earlier each day. If you’re travelling westward, shift your bedtime and wake-up time later each day.
After travel: When you arrive at your destination, continue to adjust your sleep schedule gradually. Expose yourself to natural light during daylight hours and engage in activities that promote wakefulness during the day. Aim to go to bed and wake up at the appropriate times for the local time zone.

Exposure to natural light

Before travel: Increase exposure to natural light, particularly in the morning, to help regulate your circadian rhythm. Natural light signals to your body that it’s time to be awake, helping to advance or delay your internal clock as needed.
After travel: Spend time outdoors during daylight hours at your destination to expose yourself to natural light. This can help synchronise your internal clock with the local time zone and promote alertness during the day. It is also recommended that you avoid blue light exposure (e.g. from a mobile phone) for at least one hour before going to bed.

Melatonin supplements

Before travel: Melatonin is a natural hormone that is released by your body to let your brain know when it is time to sleep. Consider taking melatonin supplements in the days leading up to your trip to help shift your sleep-wake cycle. Because melatonin regulates sleep and wakefulness, supplements help signal to your body that it’s time to sleep at the appropriate time in the new time zone.
After travel: If you’re having difficulty sleeping at the appropriate time after arrival, melatonin supplements can help the adjustment process. Some people find it beneficial to take melatonin about 30 minutes to an hour before their desired bedtime to promote sleepiness.

Special Considerations

When it comes to managing jet lag, travellers with specific needs, such as children or those with medical conditions, can face unique challenges. It is important to be aware of any special considerations so you can tailor your plan for managing jet lag accordingly.

Children

Maintain routine: Try to maintain familiar routines, such as mealtimes and bedtime rituals, during travel. It can also help to bring any favourite teddies or comfort items and continue with routines such as reading a story before bed. Consistency can help children feel more secure and comfortable in unfamiliar surroundings.
Encourage activity: Engage children in light physical activity and playtime during stopovers or upon arrival at the destination to help them stay awake and adjust to the local time. Burning energy can also help with resetting the body clock.
Consider night flights: Children typically find it easier to sleep on flights compared to adults, particularly because they are smaller so are less likely to be uncomfortable in the plane seat and also because children are more reliant on sleep than adults. A night flight allows your child to sleep and arriving at the destination in the morning gives them a chance to adapt to the new time zone and environment.

Individuals with medical conditions

Consult your doctor: If you have a medical condition, you should consult your primary healthcare provider before travelling, particularly if you have any concerns about managing jet lag. Certain medical conditions or medications may interact with strategies for coping with jet lag, so it is essential to seek personalised medical advice.
Medication management: Ensure that you have an adequate supply of any necessary medications for the duration of your trip. Discuss with your healthcare provider the timing and dosage of medications to accommodate changes in time zones. Make sure you pack any medication that you will need during your flight in your hand luggage.
Comfort aids: Prioritise comfort during travel, particularly if you have mobility issues or chronic pain. Bring any necessary assistive devices or comfort aids to ensure a comfortable journey and pack pain medication if necessary.

Elderly travellers

Stay comfortable: Over 60s are twice as likely to experience jet lag compared to people in their 20s. Comfort aids, such as travel pillows, a travel footrest and a pain-relieving seat cushion, can help to make the flight more restful, decrease pain and help you to sleep.
Compression socks: Elderly people are at higher risk of blood clots and may find it more difficult to move around the cabin during the flight. Compression socks can help the blood circulate to your lower extremities and your heart more effectively, reducing the likelihood of blood clots.

Pregnant travellers

Consult your doctor: Pregnant travellers should consult their healthcare provider before travelling, particularly if they have concerns about managing jet lag or want to discuss any potential health issues or pregnancy complications before the flight. Discuss any specific recommendations or precautions based on individual health status and the stage of pregnancy.
Hydration and nutrition: Staying hydrated is one of the best ways to reduce jetlag. Drink more water than you would usually. It is also recommended to pack snacks, particularly if you experience nausea or have certain foods that you feel comfortable eating. Eating healthily before and during the flight can help to reduce the symptoms of jet lag.
Move around the cabin: Pregnant women may experience increased fatigue and discomfort,so it is essential to take breaks and move around periodically to promote circulation.
Pregnancy pillow: A pregnancy wedge pillow can help you be more comfortable in your seat and can help ease the pressure on your back or stomach.

By addressing the unique needs and challenges of individual travellers and implementing appropriate strategies, it is possible to manage jet lag effectively and ensure a safer, more comfortable and enjoyable travel experience for all involved.

Prevention and Planning

Jet lag often improves after a few days; however, for some people, it can take a few weeks. Planning ahead can help minimise the impact of jet lag. Choosing flights that align with your natural sleep-wake cycle, if possible, can reduce the severity of symptoms. Whenever possible, choose direct flights to minimise stopovers and reduce overall travel time. Direct flights can help you arrive at your destination more quickly and lessen the disruption to your sleep-wake cycle.

Some travellers prefer to take overnight flights, commonly referred to as red-eye flights, if they align with their natural sleep schedule. Sleeping during the flight can help you arrive at your destination feeling more rested and better prepared to adjust to the local time. However, if you find it difficult to sleep on planes, an overnight flight can cause you to lose a night’s sleep which can worsen the symptoms of jet lag.

Planning ahead is also recommended. Familiarise yourself with the time zone of your destination and anticipate the potential effects of jet lag based on the direction of travel and the number of time zones crossed. To prevent jet lag from occurring, you can pre-adapt your internal clock. Adjusting your sleep routine in the 48 hours before your journey can be advantageous and can minimise the disconnection between your body’s internal clock and the time at your destination upon arrival. Gradually shift your bedtime and wake-up time to help your body adapt more smoothly upon arrival.

Additionally, setting realistic expectations regarding the duration and intensity of jet lag symptoms can help travellers cope more effectively. Proper preparation and proactive measures can make a significant difference in managing jet lag and ensuring a smoother transition when crossing multiple time zones. Be patient with yourself and allow for an adjustment period before expecting to feel fully back to normal. It can also be helpful to recognise that jet lag may temporarily affect your energy levels, concentration and productivity upon arrival at your destination. Plan accordingly by scheduling lighter activities or allowing for additional rest during the first day or two of your trip.

It can also be beneficial to focus on your nutrition and hydration, before, during and after your flight. Drink plenty of water before, during and after your flight to stay hydrated and combat the effects of air travel on your body. Avoid excessive caffeine and alcohol, as they can contribute to dehydration and disrupt your sleep-wake cycle. You should also maintain a balanced diet leading up to your trip and during your travels. Choose nutritious foods that provide sustained energy and support overall well-being.

It is also important to consider how to overcome jet lag on short trips, for example, if you are travelling across time zones for a three-day trip. Some people choose not to reset their circadian rhythm on short trips to avoid jet lag on their return home. For example, you may choose not to change your sleeping or eating schedule too drastically to avoid needing to change it again in a few days.

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