I'd have paid good money for this these last few days.

So you've exhausted all your options - melatonin, prescription sleeping pills, alternative therapies such as lavender oil, changed your eating times and got some exercise - and still can't seem to beat jet lag?

Next time, try some good old mathematics for a change. Researchers at the University of Michigan have created a free iPhone app that offers users lighting schedules that they say are mathematically proven to adjust you to new time zones as quickly as possible.