When you’re visiting a different country for a holiday, or for work, the effects of jet lag can be a considerable inconvenience.

Anticipating this, it’s unsurprising then that many travellers will turn to their doctor for help before embarking on a long trip. However, the use of medication to ‘treat’ jet lag is a subject which splits opinion.

What is jet lag?

The term jet lag refers to the symptoms caused by crossing several time zones in a relatively short space of time. Also referred to as desynchronosis or flight fatigue, this condition can disturb your daily routine, as your body struggles to regulate when it should be awake and when it should sleep.

Our circadian rhythm is our internal clock. It goes through a certain cycle each day, and influences sleep, body temperature, blood pressure, hormones, hunger, thirst and the release of glucose.

Jet lag occurs when our natural circadian rhythm is disrupted, due to moving into a new time zone.

Crossing one or two time zones does not usually cause too much trouble; it’s when someone travels across three or more time zones where problems may arise.

What are jet lag symptoms?

The shift in time zone can cause a number of symptoms, and the severity of these tend to relate to the number of time zones crossed, and also the direction in which they were crossed. Travelling in an easterly direction (when you effectively lose time) is usually worse than travelling westwards.

The most obvious symptom related to jet lag is sleep disruption, but other common jet lag symptoms include:

  • Drowsiness
  • Lethargy
  • Stomach problems
  • Nausea
  • Lack of concentration
  • Reduced appetite
  • Irritability
  • Confusion
  • Muscle soreness
  • Indigestion
  • Diarrhoea
  • Constipation
  • Sweating
  • Anxiety
  • Headaches

The severity of the above can vary from person to person.

Why do we experience jet lag?

Melatonin (known to many as the ‘sleep hormone’) is a hormone released by the pineal gland during the evening, and into the darker hours. Melatonin is produced by us on a daily basis, and its release is synced to natural daylight and darkness. It triggers different physiological responses in different animals. In humans, it essentially gets our bodies ready for sleep.

When we fly through numerous time zones, this hormone release does not instantly adjust to the new schedule, so our internal clock essentially becomes out of sync. In fact it can take several days for our circadian rhythm to adjust to our new environment. It is thought that our bodies will take one day for each time zone crossed to adjust.

How can I minimise jet lag symptoms?

There are several self-help measures which can assist in limiting the effects of jet lag:

  • Mimic your new schedule before you leave. If you have a long haul flight coming up, you might find it beneficial to slowly adjust your bedtime to one closer to that of your destination before you depart. This means that when you land your body will be more prepared for the changes in sleep times.
  • Drink water. Stay hydrated on the flight. Dehydration will only exacerbate any jet lag symptoms and make you feel sluggish.
  • Move about. A long haul flight often means sitting still for an extended period of time. Where possible you should try to remain active during your flight. Aim to get up and walk about the cabin throughout the flight and carry out some stretches when you are seated.
  • Adapt to your new schedule. Try to get used to your new time zone as soon as possible. When you board your flight, change the time on your watch to that of your destination. It is also a good idea to try eating and drinking at the usual times for your new location and staying awake until a reasonable local bedtime.
  • Avoid alcohol and caffeine. Both are sleep inhibitors, so it’s better to steer clear of them when adjusting to a new time zone.
  • Sunlight exposure. To help your circadian rhythm adjust to your new location, try and get out in the daylight as soon as possible. If you have travelled in an easterly direction aim to get out in the bright morning light. If you have travelled in a westerly direction, try and expose yourself to early evening light. Fresh air may also help you avoid hitting the hay too early.

If you arrive at your destination and find yourself unable to stay awake, try to limit the amount of sleep you have initially.

What medications are used to treat jet lag?

There are no specific medications licensed to treat jet lag in the UK.

Sleeping pills are typically not advised, as the use of these can lead to dependence.

Melatonin is considered by some to be an effective jet lag treatment. But this medication, available under the brand name Circadin, is licensed in the UK for use in primary insomnia, in over 55s; it is not specifically licensed for jet lag, and can only be prescribed for this purpose 'off-label'.

The use of jet lag remedies and supplements which contain melatonin is reportedly fairly widespread in the US; some treatments are even available over the counter. According to survey data from the National Center for Complementary and Integrative Health, 3.1 million American adults use melatonin to relieve jet lag or other sleep related disorders.

In treating jet lag, the idea is that the melatonin contained in the medicine helps to supplement levels of the hormone in the body, and thereby helps us sleep.

A 2002 Cochrane review of 10 studies observed that melatonin had shown to be ‘remarkably effective’ at preventing and relieving jet lag in those who have travelled across five or more timezones, particularly in an easterly direction. But the authors did note that more research was needed, and that taking it at the wrong time could serve to delay acclimatisation.

NICE guidelines on jet lag do not recommend the use of melatonin: because evidence to support its use in this scenario is not conclusive; and also because other factors related to its use in jet lag, such as the most effective dose and the long term effects of the drug, remain unclear.

Further advice

If you are travelling long-haul and are concerned about jet lag, we would recommend speaking to your doctor. They will be able to provide further advice on what to do before, during and after your flight, to help you adjust to your new time zone, and limit jet lag symptoms.