Jet lag happens when you move rapidly between time zones leaving your usual circadian rhythms out of sync with your new sleep/wake-up schedule. Common symptoms include sleepiness during the day, decreased alertness, difficulty concentrating, impaired performance, gastric discomfort and difficulty falling/staying asleep at the end of the day.

It can take circadian rhythms several days to shift to a new sleep/wake schedule but if you have business negotiations lined up, are taking part in a sports event or simply want to make the most of your hard-earned holiday you'll want to be feeling your best as soon as possible.

Research shows that following a 'light schedule', particularly if you start it before your trip, can help the body to adjust more quickly.

This tool is based on published scientific research including work from Surrey Clinical Research Centre. This is a world-leading centre for sleep studies and we're particularly grateful to chronobiologist Dr Vikki Revell for her help with the calculations.

For more information read the guide beat jet lag with light therapy and also check out Zest, a travel-size bright light you can use with your jet lag plan.

Time zone difference
What time do you normally wake up?

Calculate Jetlag plan