Fighting jet lag? Smartphone app takes mathematical approach to getting you back on your feet

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.

The app Entrain was launched this month, and is believed to be the first to take a numbers-based approach to "entrainment" - the scientific term defined as "alignment of an organism's circadian rhythm to that of an external rhythm in its environment".

"Overcoming jet lag is fundamentally a math problem and we've calculated the optimal way of doing it," says Danny Forger, a professor of mathematics at the university's College of Literature, Science, and the Arts. "We're certainly not the first people to offer advice about this, but our predictions show the best and quickest ways to adjust across time zones."

The foundation of the app is two sets of equations devised by Forger and colleagues in the '90s that have been shown to accurately describe human circadian rhythms, or the body's biological clock. The clock is regulated by light, particularly from the sun and in wavelengths that appear to our eyes as the colour blue.

The researchers used the equations and a technique called optimal control theory to calculate ideal adjustment schedules of light and darkness for more than 1,000 possible trips. A detailed explanation of the math is published in a study in PLoS Computational Biology.