If I had to fly standing on my head to avoid the jet lag unleashed by 13 time zone changes, I would have. Instead, while everyone else dined on the night flight to Singapore, I sat in the dark, and, after we arrived, rotated like a sundial around a south-facing office window.

This jet-lag remedy was prescribed by Timeshifter, an app that is among a spate of new approaches to what scientists say is the cause of jet lag: Out-of-whack circadian rhythms, also known as your 24-hour biological clock.

Circadian science, newly embraced by airlines, hotels and airport lounges in the form of light therapy, prescribes bright light for wakefulness and warm light to prepare to rest. Light exposure helps reset the clock, according to the National Sleep Foundation.

“Nearly all species have an internal or circadian clock which has evolved to allow us to interact with the outside world,” said Steven W. Lockley, a sleep expert and associate professor at Harvard Medical School. He has worked with NASA astronauts using circadian science to boost their alertness, and is a partner in Timeshifter. “It anticipates environmental time so we can be ready at the right time to find food, avoid predators and find a mate,” he added.