Post-Covid lockdowns, long-haul flights are back for a long time but rarely a good time. Australia and New Zealand’s home at the bottom of the globe means many of us are no stranger to long-haul flights. That means we’re also unpleasantly acquainted with jet lag, that woozy, unsettled sluggishness that some people describe as a mix of feeling exhausted, slightly drunk or like you’ve been hit by a truck.
As Australia’s national carrier, Qantas, invests more in ultra long-haul flights – such as its new Sydney-Auckland-New York service – jet lag isn’t going anywhere in a hurry. But research into the phenomenon is uncovering new ways to keep it at bay.
The sleep scientist’s method: adjust your exposure to light
What is jet lag, anyway? Dr Svetlana Postnova, a biological physicist from Charles Sturt University who has been studying sleep and circadian rhythms for more than 18 years, knows the answer.
She explains that each of our cells contains a circadian clock, and those clocks control the timing of everything that happens in our body, from sleep to hormone levels. Jet lag occurs when our internal clocks are misaligned with the environment, which affects everything from tiredness to food cravings.
By controlling your light exposure, you can help those clocks adjust. Sitting in bright light at the right time of day or night either delays or advances your circadian clock, bringing it closer to the environment you’re travelling to.
With this front of mind, Postnova and her colleagues have been conducting experiments with Qantas, to see if adjusting the lights on long-haul flights – such as the new 16-hour non-stop flight from Auckland to New York – helps minimise jet lag.
Instead of keeping the cabin in darkness for most of the journey, which is what airlines typically do, the scientists tailored the timing of light exposure on the flights to help their subjects shift their clocks in the right direction.
Compared with a control group, their findings were small-scale but promising. “Self-reported jet lag was shorter in the optimised group,” Postnova says. “And we also saw that their objective alertness was higher for two days after the flight.”
If you’re not flying on a light-optimised flight, you could try to adjust your light exposure yourself, though Postnova acknowledges this can be “tricky”. You need to account for how far ahead or behind the destination is from your home, and whether you’re flying east or west.
Then, you should blast yourself with an hour or so of bright light in either the early morning, or after dark, for a few days to help shift your clock in the right direction. “You could also use the entertainment screen on the flight for a bit of light exposure,” she says.
If you were flying from Sydney to London, a trip which takes you “backward” by between seven and nine hours, you would adjust by delaying your sleep and exposing yourself to bright light in the afternoon and evening before you fly, while avoiding morning light, Postnova says. Whereas if you were flying back from Europe (taking your body clock “forwards”) you would want to start waking up earlier and seek light in the early morning.
But, Postnova cautions that how you adjust will depend on how much you go backwards and forwards in time. Once the time difference between where you’re arriving and where you’re leaving is above 12-14 hours, it may be easier for your body clock to adjust by going the opposite way.
That complexity is why, ultimately, she’d like to see airlines doing the hard work for you. “It would be nice to see more flights
