The holidays are coming!
For many of us, that means wrapping up warm and hibernating at home, but you might be lucky enough to be jetting off on a long-haul flight. If you only have a short time away, the last thing you want is to ruin it with the sleeplessness and grogginess of jet lag.
So, in this article we ask: what causes jet lag, and what can you do to prevent travel fatigue?
What is jet lag?
We are programmed to wake and sleep according to a 24 hour, or ‘circadian’ rhythm. Every cell in our bodies carries an internal clock. Under usual circumstances, this clock is aligned with the light-dark cycle of the sun so that we feel active during daylight hours and sleep during the night.
When you fly across multiple time zones, your internal rhythms don’t have time to adjust their timing to fit the new environment. This might mean that you try to eat when your body clocks are anticipating sleep or get into bed at a time when your internal clocks are telling you to be wide awake, for example.
Jetlag is a mismatch or misalignment of our internal circadian rhythms and our environment which can make us feel disorientated and unwell. Most people start to experience the symptoms of jet lag when they fly across more than 3 time zones.
What are the symptoms of jet lag?
When most people think of jet lag, they think about feeling sleepy during the day, or not being able to sleep at night. Sleepless nights are the most obvious effect of being out of sync with local time, but jet lag can also mean that some of our internal clocks fall out of sync with each other. Virtually every system in the body can be affected by jet lag. The symptoms include:
●Difficulty falling asleep, or staying asleep
●Lack of energy
●Feeling generally unwell, headaches, dizziness
●Irritability, and a worsening of existing mood problems
●Stomach and GI upsets, changes in appetite, nausea, constipation, irritable bowel symptoms
●Cognitive problems, including poor concentration and memory lapses
●Parasomnias, such as sleep walking, sleep talking and sleep paralysis
●In rare cases, severe jet lag has also been linked to seizures
How long does jet lag last?
As a rule of thumb, it takes about 24 hours for your internal rhythms to adjust for every hour of time zone that you have crossed. However, there is a lot of individual variation. Some people are simply more prone to jet lag than others. You will find it easier to adjust if you start your journey well rested, whereas stress can interfere with the rate of recovery.
Read on to find out about the steps you can take to accelerate your adjustment to a new time zone.
How to avoid jet lag: managing light exposure is key
Bright light is the key signal that our bodies use to keep internal rhythms co-ordinated with each other, and our environment. Bright light lands on receptors at the back of eye and sends an alerting signal to a master clock in the brain called the suprachiasmatic nucleus (SCN). The master clock triggers the release of serotonin, and the brain becomes more alert. Darkness, or dim light, is the brain’s signal to produce melatonin, the hormone which helps to prepare the body for deep sleep.
●Being exposed to bright light at dawn or early morning in the time zone of our departure has the effect of advancing the master clock and making us feel sleepy earlier. This is helpful if you’re flying east.
●Bright light late at night in the time zone of our departure has the effect of delaying the master clock and making us sleepy later. This can be helpful if you’re flying west.
If you’re flying East, e.g. New York to London (+5hrs), the effect on your body clock is to make the day shorter. You can start to go to bed and wake up an hour earlier 2 days before you fly.
On arrival, ask yourself… what time is it for my body clock i.e. what time is it at the place you departed from? If it’s after sunrise and before sunset, seek out light. If it’s between sunset and dawn, avoid light by dimming the lights or wearing wrap around sunglasses.
If you’re flying West, e.g. London to New York (-5hrs), the effect on your body clock is to make the day longer – you want to behave more like a night owl. You could start to go to bed an hour later and wake up an hour later 2 days before you fly.
On arrival, ask yourself… what time is it for my body clock i.e. what time is it at the place you departed from? Being exposed to light between sunset and dawn will delay the body clock. Minimise light in your old morning zone to help delay the clock.
Try to arrive in the afternoon/evening in time to have a full night’s sleep at your new destination. Ideally, avoid cutting short your sleep on the day of departure, so that you fly after a good night’s sleep.
Although light is the most important signal of time to your body clock, food, intense movement and temperature changes can also alert the body clocks. These signals are called ‘Zeitgebers’, or time givers.
Timeshifter is an app you can buy to give tailored advice about when to seek out bright light, and when to avoid it, based on your schedule and flight times.
Why is it easier to fly west?
You may have heard the saying ‘West is best, East is a beast’. Our internal rhythms naturally run at slightly longer than 24 hours. So, we tend to find it easier to extend our days by flying west than we do to compress our days by flying east.
Sleeping on a plane: things to consider
Change your watch when you get on the plane and stick to the sleeping and eating schedule that you’ll have on arrival. This may not be when you are served food on the flight. Aim to take snacks with you. An apple is good for slow-release energy. If in doubt, skip a meal – it’ll be easier to adjust than over-eating.
Always travel with an eye mask and ear plugs. If you can’t sleep, you can still rest. I usually fly in comfortable clothing including a hooded sweatshirt so that I can pull the hood over my head and block out the outside world!
Be wary of drinking more caffeine than usual and ask for decaf if you’re planning to sleep on the plane. Alcohol will disrupt the quality of your sleep and make you more dehydrated.
Stand up and move as frequently as possible when you’re not sleeping. This will reduce the risks of stiffness and blood clots. You can also do gentle stretching in your seat, even with the seatbelt sign switched on!
Why does travelling make you tired?
If you fly north-south, rather than east-west, you may still notice that you feel fatigued, even though you haven’t crossed any time zones. The process of travelling can still be exhausting. late night packing, early starts, walking around the airport, sitting in a cramped position on the plane, breathing lower oxygen recycled air, dehydration, irregular sleep and eating patterns can all take their toll.
There is also the mental stress associated with uncertainty and a lack of control and familiarity. We know that when you sleep in a new place your sleep tends to be lighter as your brain stays on edge, looking for danger. This is called the ‘first night effect’.
Tips to reduce travel fatigue
●Write yourself a checklist for packing in advance. This is mostly so you don’t have to waste energy worrying about what you’ve forgotten or buy yet another travel plug adaptor at the airport (I have 5). My list includes, passport, phone, eye mask, ear plugs, empty water bottle, lip balm, phone charger, wallet and printouts of travel insurance, flight details, and accommodation.
●Can you avoid an early flight? A 7am flight could mean waking up at 4am. The stress of anticipation inevitably means that you end up waking up at 2am, 3am and 3:55am, so you’re compressing your sleep before you’ve even started. Consider staying at the airport for a full night’s sleep, and wherever possible, bank extra sleep a few days before you fly.
●Allow for the unexpected and leave plenty of time so that you’re not rushing. Trying to find an address when the wifi goes down or the battery runs out on your phone can get stressful, so take printouts of where you’re going!
●To make it easier to sleep in a new environment, try to repeat the same wind down routine that you use at home. A warm bath or shower, reading a familiar book, or a spot of meditation can help to detach from the excitement of the day, and get the mind and body ready for sleep.
●Take a few things which are familiar from home - favourite pyjamas, a book, photos, or even a pillow.