Many of us who have been on a long-haul flight will be familiar with jet lag. With this in mind, Dr David Garley’s latest article examines jet lag and how it affects us. We’ll also look at the best ways to deal with jet lag, allowing for complete peace of mind when you travel abroad.
Before understanding jet lag, you first have to understand the concept of the circadian rhythm, also known as your internal body clock. This is our bodies’ natural rhythm, and it features day and night phases.
The circadian rhythm has evolved in humans due to our reliance on daylight for most of our activities, making us naturally more active during the day and inclined to rest at night. This rhythm persists, maintaining its steady influence over our daily cycles.
Our circadian rhythms are influenced by things called ‘time givers’; the most important is light. Light keeps our circadian rhythms in check and helps us adapt to the changing hours of daylight that come with different seasons.
When a circadian rhythm is behaving properly, it kicks into action just before you wake up and continues to rise, making you feel bright and alert throughout the day. It then takes a downturn in the early evening before moving into the sleep phase at your usual bedtime, which helps you sustain sleep throughout the night.
Jet lag is a problem that arises when a person with a perfectly functioning circadian rhythm gets on a plane and is flown into a time zone several hours out of sync. As a result, the circadian rhythm is no longer in sync with the local time zone.
This means that at your destination, the local time might be 1:00 in the morning, and everyone is asleep, but your body thinks it’s only 7:00 PM and is, therefore, wide awake. Alternatively, it may be 3:00 PM your local time, but your body thinks it’s the middle of the night, meaning you’ll struggle to stay awake. This can cause problems such as sleepiness and fatigue during the day and an inability to fall asleep at night.
The degree to which jet lag affects you can vary from person to person and is also influenced by the activities you carry out.
For instance, if you are on an important business trip and need to do a high-pressure presentation, daytime sleepiness could be a real problem. However, if you are going on holiday and have nothing more to do than relax on a beach during the day, you are unlikely to be affected in the same way!
Jet lag can also cause more problems if you fly east. When you fly eastwards, you arrive later in the day than your body thinks. This means your bedtime at your destination will be early, and trying to sleep early is often extremely difficult.
Conversely, when you fly westwards, you arrive earlier than your body thinks. This means it’s like trying to go to sleep later than your body thinks it is – and going to bed later is much easier than going to bed earlier.
An important distinction here relates to the usual fatigue a person can feel when travelling all day, known as travel fatigue.
Jet lag usually occurs when you have crossed at least two time zones. However, if you have spent all day travelling yet remain in the same time zone, you will likely remain tired. This type of fatigue will settle after a good night’s rest.
With long-haul travel across time zones, you’ll likely experience both travel fatigue and jet lag.
Another type of jet lag is called social jet lag. This doesn’t involve long-haul travel but describes the circadian disruption that can occur with irregular sleep times.
Often, this can be through lots of late-night socialising, but it can also arise from other responsibilities that require irregular schedules. It is very similar to the circadian problems that arise from shift work.
Circadian rhythms can be your best friend by making you feel bright and alert during the day and sleepy at night. However, it’s important to maintain a consistent sleep schedule. Otherwise, your circadian rhythm can become weak and inconsistent and promote sleep when you want to be awake and wake when you want to be asleep.
When crossing multiple time zones, you will experience a degree of jet lag, but it can be reduced. The approaches can be categorised into pre-travel, during travel, and arrival.
You can reduce the effects of jet lag by gradually adjusting your schedule before your trip. By manipulating your exposure to the ‘time givers’, such as light, you can shift your circadian rhythm in the direction you must be in on arrival.
For example, if travelling west, you could aim to go to bed thirty minutes later and wake up thirty minutes later for a few days before departure. Exposure to bright light in the evenings can trick your brain into thinking it’s earlier than it is and potentially shift your circadian rhythm.
If you’re flying east, you can adjust your circadian rhythm before your trip by waking up earlier and exposing yourself to bright light in the morning. A practical way to do this is to take a sunrise walk and ensure your lights are turned down low that evening. However, the way you time light exposure varies if you travel across more than nine time zones.
If you can adapt to the destination time zone as soon as you board the plane, this could make a significant difference.
Many long-haul flights now take this approach and ensure the cabin lights are turned on to match the destination time zone. Caffeine, on the other hand, can help promote wakefulness when required.
Staying awake during the flight is often helpful for westward travel. The increased tiredness that comes with this can help you fall asleep when out of sync in the later destination time zone. Whilst sleep will never be as good as it is while you’re home in bed, you can make the most of the situation by investing in noise-cancelling headphones and eye masks.
Upon arrival, it is best to adapt to your local time zone as quickly as possible. Thorough exposure to time givers, such as light, exercise, and meal times, can reinforce this.
Bright light and exercise early in the morning help remind your body that it is in the wake phase of the circadian rhythm.
Another way to speed up the time it takes to adapt to your new time zone is to take melatonin. Melatonin is the hormone of your sleep phase, and taking this as a tablet at the right time can move your circadian rhyme forward or back.
Please note, that this has to be prescribed by a GP or sleep doctor.
The reality of long-haul travel is that you will always experience a degree of jetlag, but what helps is knowing what to expect and being prepared.
Knowing that this will settle in a few days can help with any anxiety that may build up, and following the steps described above can help shorten the time it takes your circadian rhythm to go back into sync.
If you’d like to learn more about the science behind sleep, check out www.thebettersleepclinic.co.uk.