When you cross time zones, the pineal gland -which controls your body's temperature and internal clock -is disrupted by the change in light, playing havoc with your natural rhythms. The World Health Organisation warns that the effects are far greater than problems with sleep -jet lag can cause indigestion issues, disturbance of bowel function, blood pressure fluctuations and general malaise.

BEFORE YOU FLY

THINK AHEAD

Start preparing the week before you travel. Get good sleep, exercise regularly (preferably outdoors), eat healthily, avoid caffeine and keep yourself hydrated.

STAY ACTIVE

At the airport, move around as much as possible. Sitting around before you fly is the worst thing you can do -stay active before the flight and you won't feel as sluggish when you board.

Once on the plane, stretch and move around regularly as this will improve blood flow and stop you from feeling too lethargic.

EAT WELL

On the day you're traveling, and once you arrive at your destination, make sure you eat a healthy meal with fresh fruit and vegetables.If possible, you must try and avoid caffeine, refined sugars and heavily salted plane food.

Take snacks on board with you such as oat cakes, nuts and dried fruit, crudites and fresh fruit.


DRINK WISELY

Stay hydrated and avoid stimulants. Take a large bottle of water on the plane with you, and herbal tea bags so you can have a caffeine-free hot drink.

MEDITATE

Close your eyes and meditate on take-off and landing for 20 minutes each time. Breathe in deeply, and imagine putting down roots as you exhale.

Imagine those roots going all the way down to the core of the earth, anchoring you.

RELAX

Watch a relaxing film, listen to music, or read. If you start feeling sleepy, switch the film off or put the book down, and prepare to rest rather than dozing off during an activity. If you have to work, do so for short amounts of time.

REST

Put the emphasis on resting rather than sleeping. Dot lavender oils or eucalyptus on your flight cushion to help you relax, and use an eye mask and ear plugs.

Put a `DO NOT DISTURB' sign on your table if you don't want to be woken for meals or duty-free shopping trollies.

GO NATURAL

Avoid medication to help you sleep as your body needs to naturally adjust to the time zone. If you can't sleep, think about having a rest -it's likely you will drift off anyway.

ONCE YOU ARRIVE DON'T NAP

Try to hold off on napping as you need to synchronise your internal clock to your destination.If you must nap, do it between 2-4 in the afternoon and sleep for a maximum of 20 minutes. Eat light food, as feeling too full will add to your tiredness.

DON'T CLOCK-WATCH

Change your clock to local time immediately and don't keep thinking about what the time is at home -this will only make you feel worse.