How to get over jet lag: before, during and after the flight.

You land at seven and at nine you're in the meeting you flew out for. In the taxi you search how to get over jet lag and find pills and tricks. What shifts your body clock is free: light, meals and movement, at the right time.

"I'm at half speed for a week," frequent flyers I work with often tell me. The mistake I see most is sleeping as soon as you arrive. It eases the tiredness, but your body clock usually stays on home time.

Jet lag symptoms

• Sleep back to front. Eyes closing by day, staring at the ceiling by night.
• Slow head, short fuse. You struggle to concentrate and snap over nothing.
• A gut on the wrong timetable. Hungry at 3am, no appetite at lunch.

How long does jet lag last?

As a rule, almost a day for every hour of time difference. With six hours, nearly a week. Flying east it usually takes a little longer, flying west a little less.

Why east costs more. Flying west, your day gets longer and your body clock only has to run late. Flying east it has to run early, and your body stretches its cycle more easily than it shortens it.

Your low point has a time. Body temperature bottoms out between three and five in the morning, home time, when the pull to sleep is usually strongest. For the first few days, six time zones east puts that at roughly nine to eleven in the morning, local time. Six zones west, the same hours at night.

Even one hour counts. When the clocks change, the effects can last up to three weeks. And recovery tends to slow with age.

What to do: before, during and after

Three days before, start shifting. Nudge sleep, meals and light towards destination time, earlier going east, later going west.

On the plane, set your watch to arrival time. If it's night at your destination, eye mask on and try to sleep, as lost sleep slows recovery. Sip water, skip alcohol and coffee. Flying dries you out.

When you arrive, use light by direction. Flying east, get outside in the morning without sunglasses, and keep lights low and screens off in the evening, when bright light tends to push your clock later. Flying west, stay outdoors in the late afternoon. Sleep in complete darkness. The contrast is the signal.

Eat and move on local time. From your first meal. Eat light when a meal falls in your night at home, as your liver and gut are usually slower then. Coffee only in the first part of the day, local time. On day one, a walk outdoors is enough. Hard training, short sleep and a new time zone together are usually too much.

Before you leave, decide when you need the light. Hotel rooms and eating on the road have their own articles.