Jet Lag

Jet lag refers to the symptoms that you experience after flying to a different time zone as your body adapts to a different light-dark schedule. These symptoms can affect anyone.

You may find that your sleep is disturbed and you feel lethargic during the day. Jet lag is very different to travel fatigue, and it cannot be reduced by using certain aircraft, more comfortable seating, or upgrading to first class.

What are circadian rhythms?

Circadian rhythms are variations in body functions that change over 24 hour periods, controlled by "biological clocks" in your body. Jet lag strikes when your biological clocks are out of step with the light-dark schedule in a new time zone.

The cells in your body have their own clocks that are controlled by a master clock in your brain. This keeps all of the cell clocks in time with each other and the light-dark rest-activity schedule that is set by your normal daily activity.

Circadian rhythms control your sleeping and waking pattern, appetite, digestion, bowel habits, urine production, body temperature, and blood pressure.

Your body gets used to a certain light-dark schedule, and struggles to adapt when you move to a new time zone. You will stop feeling jet lag symptoms when your body has adjusted its circadian rhythms.

Most people report that jet lag is worse flying east than flying west.

Flights that cross seven to 12 time zones generally cause more severe jet lag than those that cross three to six time zones. Most people will not suffer jet lag if they cross one or two time zones.

Jet lag causes different symptoms in different people. Symptoms will be more severe if you cross at least three time zones.

The most common symptom of jet lag is sleep disturbance. It may be difficult to get to sleep at night, and you may feel sleepy during the day.

Other symptoms of jet lag include:

• Indigestion
• Constipation
• Diarrhoea
• Nausea
• Loss of appetite
• Difficulty concentrating
• Feeling disorientated
• Anxiety
• Irritability
• Memory problems
• Clumsiness
• Lethargy (lack of energy)
• Light-headedness
• Confusion
• Headaches
• Sweating
• Muscle soreness
• Irregular periods in women who travel frequently
• Generally feeling unwell

If you have flown across nine or more time zones, especially on an easterly flight, you may experience symptoms for up to six days.

The disruption of circadian rhythms is a major cause of jet lag. This means that your body is not used to the light-dark rest-activity schedule that is expected of it in your new time zone.

Flying east is another cause of more severe jet lag. This may be because it is easier for your body to get used to longer days than shorter days, and you "gain time" traveling west rather than "losing time" when you fly east. It is easier to extend your day than shorten it, for example sleeping a few hours later is easier than getting to sleep hours before your normal bed time.

Jet lag can also be worsened by general travel fatigue. This can be caused by dehydration, drinking alcohol and caffeine inflight, not sleeping, stress, and being over 60 years old.

Some scientists believe that being at high altitude and experiencing changes in cabin pressure can be enough to cause similar symptoms to jet lag, even if you don't cross any time zones.

To treat jet lag it is important to take action when you arrive at your destination. On arrival you should:

• Set a new routine and stick to it – this means eating and sleeping at the normal times for your new time zone, not when you would at home.
• Don't nap on arrival – try to remain active until a normal bedtime for your destination.
• Spend time outside – natural light helps to get over jet lag.

There are other ways of treating jet lag as well. The first is melatonin, a substance that is produced by your body in the evening to prepare you for sleep. There are jet lag remedies available which contain melatonin, which you should take to help you get to sleep in your new time zone.

Some people find it helpful, but there is not enough evidence to conclude whether melatonin can treat jet lag or not. You will need a prescription to get hold of melatonin pills in Australia.

Another option is sleeping tablets. These medicines will put you to sleep at a normal time for your time zone if you take them correctly.

Doctors do not advise using sleeping tablets for jet lag because there is a risk of dependency. They can also cause side effects such as a runny nose, diarrhoea and headaches.

It is impossible to completely prevent jet lag, but there are some things that you can do to try and minimize its effects.

• Try to book flights that arrive in daylight, which will make it easier for you to stay awake. Certain planes can also help thanks to technological systems on board, so try and fly on newer aircraft.
• If you book a ticket with a stopover, it will be easier for your body to adapt. Use online booking services to find stopovers that could even cut the price of your ticket.
• Before you fly, try to change your sleep routine for a few days. If you are flying east, go to bed an hour earlier than normal. If you are flying west, go to bed an hour later. This will help to prepare your body for a different rest-activity schedule in your new destination.
• It is also important to get enough rest before you fly. If you are already tired when you fly the symptoms of jet lag may be worse when you arrive.
• During the flight you should drink a lot of water. Staying hydrated before, during and after your flight is of paramount importance.
• Take short naps so that you arrive rested. Taking an eye mask in your hand luggage will help you to get some rest. Don't drink too many caffeinated drinks, and avoid alcohol.
• Walk around the cabin during long flights and make sure to stretch your arms and legs. This will help to prevent deep vein thrombosis (DVT), which can cause serious complications.
• Change your watch to the time zone of your destination to help your body acclimatize more quickly. Make sure to switch off any pre-set alarms on your devices so that they don't wake you up when you are trying to sleep.
• If you are struggling to stay awake when you arrive, avoid coffee unless you need to stay awake for at least seven hours longer. Any shorter period of time means that the caffeine will disrupt your sleep. Drink water and avoid sugary drinks.

Jet lag can put your plans on hold. By taking medication and preparing yourself for a long-haul trip, you can minimize the effects.