Jet lag is the term used to describe the physiological effect on the human body resulting from rapid long-distance travel around the earth either East to West or West to East. Jet lag is caused by your body’s circadian rhythm being unable to adjust to this new time zone due to the speed of introduction. It only occurs from horizontal movements around the earth and not vertical. Jet lag typically occurs when you travel between three or more time zones, but it can also result from as little as one time zone or even the bi-annual seasonal clock change of just one hour can make you feel jet lagged.
In case you did not know; your circadian rhythm is basically your 24-hour internal clock that runs in the background of your brain and cycles between sleepiness and alertness at regular intervals. It's also referred to as your sleep/wake cycle. Your circadian rhythm works best when you have a great sleep routine, like going to bed at night and waking up in the morning around the same times, so when jet lag messes up your sleep habits it disturbs your circadian rhythm. It can make you feel very sleepy for a number of days. A suggested guideline in terms of recovery days is half the number of days when travelling East to West and two-thirds the number of days from West to East.
As with all biological matters jet lag will impact different people in different ways and individuals will take varying times to recover. The severity may also be impacted by the direction of travel, the distance travelled and the speed of travel (although since the hiatus in super-sonic flight most airplanes travel at relatively homogenous speeds).
What are the symptoms of Jet Lag?
The symptoms of jet lag include; having trouble falling asleep, having trouble waking early, sleep disturbance whilst you are asleep and changes to your digestive system. The impact of the poor sleep quality can result in fatigue, headaches, irritability and poorer cognitive effectiveness.
How can I recover from jet lag?
When you travel from West to East the effects of jet lag are slightly worse mainly because you need to advance you body clock rather than delay it. Our circadian rhythms are actually slightly longer than 24 hours so lengthening a day is easier than shortening one. Also as you are chasing the earth’s rotation your exposure to daylight is less likely than if you were to travel in the opposite direction.
There are a number of jet lag calculators online that can help you time you travel arrangements in aligned with you own bedtimes. For example British Airways created one here https://www.britishairways.com/travel/drsleep/public/en_gb
There are also a number of methods in which people can try to reduce the impact of jet lag:
- The management of light exposure is one of the most effective ways to reduce the impact of jet lag. By using light you are able to help the body to match you circadian rhythm with the expected light cycle at your destination and this method is particularity favoured by international athletes. There are many ways that this can be achieved but the most convenient way is to use special glasses to both provided blue light to the eyes to prevent the production of sleep inducing melatonin as well as blue light blocking glasses to not hinder this production.
- The second method is to use melatonin to reduce the symptoms. It is important to note that melatonin is not available over the counter in many counties, including the UK, but it available in many others such as the USA. This is a higher risk solution hence the legality of purchase situation in many countries.
- If your trip is for short periods, three days or fewer, stick to your home time routine as this will be better for some! Others may choose to rely on other short-term solutions such as caffeine or sleeping pills, but both of these are not without their disadvantages!!
Overall we recommend the use of light as the best way to limit the impacts of jet lag and if you are a frequent traveller the solutions to help this are extremely cost effective compared to time wasted on being tired in your new location whether this is an important business trip or an expensive holiday!
Finally all the things that will impact your sleep hygiene in every day life are just as relevant, if not more so, when you are travelling. These include keeping hydrated, avoiding alcohol and helping your breathing as much as possible!