Jet Lag

Jet lag disorder belongs to a group of sleep disorders known as circadian rhythm sleep disorders, meaning it is caused by a misalignment between your circadian rhythm and the day-night cycle. This is normally caused by time zone change. People who do shift-work experience a similar misalignment from working irregular hours, typically early in the morning or late at night, and is known as shift-work disorder.

Jet lag can often be confused with travel fatigue. This is discomfort caused by uncomfortable, long flights. It can cause headaches and tiredness, the difference being travel fatigue is not caused by circadian rhythm disruption.

What are circadian rhythms?

Circadian rhythms are 24-hour cycles that are part of the body’s internal clock. They are responsible internal body processes that regulate your mental and physical systems; they work by making sure vital processes are optimised at key points during a 24-hour cycle. For instance, the digestive system produces proteins to match meal times. Circadian rhythms are connected to a ‘master clock’, sometimes known as a circadian pacemaker. It is located in a specific part of your brain known as the suprachiasmatic nucleus (SCN), in the hypothalamus which is a part of your brain that is responsible for a lot of your bodily processes.

The SCN sends signals throughout the body to regulate activity. The SCN is highly sensitive to light which acts as a critical environmental cue (known as an exogenous zeitgeber) for most behaviours. This is why circadian rhythms are closely linked to day and night. Whilst there are other environmental cues that can affect the master clock, such as temperature and social activity, light has the most powerful influence on the SCN.

How do circadian rhythms cause jet lag?

The sleep-wake cycle is one of the clearest examples of how circadian rhythms work. During the day, light exposure as the sun rises causes the master clock to send signals that generate alertness. This is what helps us to wake up. As night falls, and it gets darker, the master clock sends a signal to the pineal gland which signals the production of a hormone called ‘melatonin’ that induces sleep.

Your own internal body clock will synchronise with your local day-night cycle. So when you travel to a new location in a different time zone, your body will not have adjusted to the new schedule yet. Your body will still operate as if it is the time of the country you just left, and therefore will release the relevant hormones according to those times. This will cause you to feel sleepy or stay awake at times irregular to the time zone you’re currently in.

Jet lag is mainly caused by travelling across 3 or more time zones, and symptoms may feel worse the higher the number of time zones you cross. Not everyone experiences jet lag from travelling however, some factors could mean you are more likely to get it. It could be dependent on:

• trip details - this could be the trip distance, direction of travel, destination, the amount of layovers you have and the arrival time. For instance, studies have found that eastward trips cause worse symptoms
• how well you slept before travelling - poorer sleep in the days leading up to travelling can increase the risk of jet lag
• age - research on what age groups are more affected is mixed. Some findings suggest the older you are the harder it is to recover, but other research has found that younger people experience worse symptoms. Regardless, your age may affect your jet lag
• alcohol and caffeine - these substances affect the brain in ways that disrupt your sleep, meaning if you ingest either you may be more at risk of getting jet lag
• stress - another body reaction that affects sleep, and can make it harder to cope with jet lag
• individual differences
• whether you have had jet lag before

Jet lag symptoms can range in severity. The most common symptom of jet lag is lethargy, caused by the change in sleep schedule. This can cause people to be awake when they should be asleep and vice versa. Other common symptoms of jet lag include:

• daytime sleepiness
• sleep problems and poor sleep
• impaired mental and physical function
• emotional difficulties
• general discomfort, illness or uneasiness
• stomach and digestion problems (like constipation)

These symptoms can develop immediately or within a few days after arrival. Most jet lag symptoms last for up to a day or a day and a half per time zone you cross. In rarer cases, jet lag symptoms can last for up to 6 days, so getting the right treatment can help you to enjoy your trip abroad (and return home) more enjoyable.

In the rarest cases, jet lag can result in sleep paralysis and nighttime seizures. This is where jet lag affects your sleep architecture, the structure of sleep cycles.

Can jet lag have long-term complications?

Because it is usually a short-term sleep problem, long-term effects of jet lag are scarce. This is because once the body’s circadian rhythm has adjusted to the local time, symptoms will improve. However, it can affect some groups of people long-term who experience jet lag frequently. This includes those who travel frequently (such as for business) or those who frequently take long-distance flights (like pilots or flight attendants). For these people, their circadian rhythms are out of sync chronically and cause persistent sleep problems. It could lead to insomnia, mental health disorders, metabolic disorders such as diabetes as well as predispose you to some cancers.

The key to treating and reducing jet lag is to realign your circadian rhythm with your current time zone. This requires some acclimation for longer trips, for which there are certain methods you can use.

Light Exposure

Light is the most important environmental cue for a lot of our physiological processes, but especially for sleep. Therefore, it makes sense that you can treat and reduce jet lag through strategic light exposure. Exposure to natural sunlight is the best way to align your internal body clock with the local time, as it is the strongest form of illumination and therefore has the strongest effect on your circadian rhythms. In the absence of natural light, you can use artificial light or light boxes (light therapy lamps) that produce bright light.

Melatonin

You can also use sleep aids to help you sleep at the appropriate time. The most effective sleep aid to treat jet lag is Melatonin. This is because it contains the hormone the body naturally produces in the evening, a few hours before bed, to induce sleep. As your body is not doing this naturally, you can boost your melatonin levels at the correct time by taking melatonin supplements or getting it on prescription. Melatonin is much more effective than other sleeping pills or natural sleeping aids as they do not alter your circadian rhythms, they just help you to fall and stay asleep. For that reason, it is also prescribed for insomnia. Not everybody can take Melatonin, so it’s best to get medical advice from a healthcare professional if you have any medical conditions or take other medications.

Jet lag cannot entirely be avoided, especially if the flight is extremely long and/or you’re abroad for a while. However, there are things you can do yourself to avoid or minimise symptoms throughout the different stages of your journey.

Before you travel

• change your sleeping pattern a few weeks before your destination by altering your sleeping routine in accordance with your destination
• get enough sleep before you begin your travels, flying when you are tired can make jet lag worse
• minimise stress before travelling by packing early and leaving for the airport on time

During your flight

• limit alcohol and caffeine intake
• eat healthy and light meals to prevent digestion problems
• keep active by standing up or taking walks occasionally as well as doing gentle stretches, this can prevent blood clotting (thrombosis) and stiffness
• change the time of your watch so that you are able to quickly adjust to the new time zones
• if it’s nighttime where you’re landing whilst you’re in the air, try to get some sleep on the plane. You could use earplugs and eye masks to help with any sleep disturbances
• drink plenty of water and fluids
• if you have been prescribed or have bought Melatonin, you should take it 1-2 hours before you land

On arrival

• find time to do some light physical activity outdoors like going on a walk, this will give you some daylight exposure and help you recalibrate your circadian rhythm
• avoid long naps, if you need to nap make sure it is 8 or more hours before your planned bedtime and try to keep it below 30 minutes
• continue to limit alcohol, caffeine and heavy meals

You can buy Melatonin instant-release (IR) tablets here at euroClinix on prescription for the treatment of jet lag disorder. All you have to do is fill out a consultation form with your medical history, and one of our registered doctors will review it. Once they find that you are suitable for treatment, your medication will be dispensed and dispatched from our pharmacy with next-day delivery.