If you’ve ever endured a long red-eye flight, you’ll know that your brain can’t reset itself quite as easily as your wristwatch. But why not? Researchers from The University of Maryland tried to find out why we get jet lag, technically known as desynchronosis, by mathematically modelling the brain’s circadian rhythms.
Neurons in your hypothalamus go through daily cycles that help regulate sleep patterns. External cues such as periods of daylight and darkness help to keep these cells in pace with each other, synchronising them to the rhythms of your environment.
Modelling this complex network of cells is a complicated task but, as Michelle Girvan, associate professor of physics at UM’s Institute for Physical Science and Technology explains: “We start by explicitly modelling the dynamics of a large number of cells and then use a novel method for simplifying this very large system to a single equation that can be easily analysed.”
After crunching the numbers it turns out that, left to its own devices, the brain’s natural cycle ends up lasting about 24 hours and 30 minutes. That extra half hour may not seem like much, but if you’re heading east and crossing several time zones at once it can add up to days.
And it’s different for everyone. “Some people may have a natural circadian rhythm with a period of 24.5 hours, while others may have longer or shorter natural rhythms,” says Girvan. These variations are likely what is behind people’s different experiences with jet lag. The longer the natural cycle, the worse the jet lag.
Although breaking down the complexities of our minds to mathematical clockwork might feel a bit uncomfortable, we can actually use these insights to our practical advantage. Girvan hopes that their model “can serve as a guide for developing more in-depth qualitative approaches, as well as strategies to combat circadian rhythm disruptions due to rapid cross-time-zone travel, shift work, or blindness.”
If maths isn’t really your thing, here's another illuminating method to help cure jet lag.