Whenever you travel by plane across several time zones, you’re bound to experience jet lag. But this annoyance, which can keep you up for several nights after you land and disrupts your daily routine, could now be eradicated.
Israeli researchers have found that reducing oxygen levels on the plane can ease the effects of jet lag, and this finding could help airlines moderate cabin air pressure.
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The study, recently published in the scientific journal Cell Metabolism, has found that changes in surrounding oxygen levels can reset the circadian clocks of mice. It shows that changing the concentration of oxygen in cells by just 3 percent, twice a day, will reset mouse cells’ circadian clocks. This internal clock makes it possible for organisms to coordinate their biology and behavior with daily environmental changes in the day-night cycle.
Just like humans, mice are prone to jet lag after a sudden shift in daylight hours. During Asher’s experiment, mice were left to eat, sleep and run on their wheels in oxygen-controlled environments. Altering oxygen levels during their normal sleep-wake cycle did not change their circadian rhythms, but once mice experienced a six-hour jump ahead in daylight hours, varying oxygen levels helped them to faster adapt their eating, sleeping and running habits to the new time.
For example, the scientists saw that a small drop in oxygen levels 12 hours prior to the six-hour daylight shift, or two hours afterwards, put the mice back on their circadian schedules faster.
Many biological processes follow a set timetable, with levels of activity rising and falling at certain times of the day. Such fluctuations, known as circadian rhythms, are driven by biological “clocks” based on a 24-hour period. The body’s master clock, residing in the brain, synchronizes a multitude of peripheral clocks present in every single cell. Disruption to this optimum timing system in both animal models and in humans can cause imbalances, which can even lead to such diseases as obesity, metabolic syndrome and fatty liver, among others.
Light, eating times and temperature are the major timing cues that synchronize circadian rhythms. But Dr. Gad Asher of Israel’s Weizmann Institute hypothesized that oxygen might also influence circadian rhythms, since its absorption in animals is linked with nutrient ingestion and maintenance of body temperatures.
The researchers suspected that a protein called HIF1α, which responds to changes in oxygen levels, was somehow involved. Indeed, they found that cells deficient in HIF1α fail to synchronize in response to oxygen variations, providing evidence that HIF1α is the molecular link between changes in oxygen levels and the resetting of circadian clocks.
“It was extremely exciting to see that even small changes in oxygen levels were sufficient to efficiently reset the circadian clock,” Asher said in a statement.
Presently, commercial airliners pressurize cabins to the same air density of a city 6,000-8,000 feet above sea level. This low-pressure saves wear and tear on the airplane, but so many passengers suffer from airsickness in response to this drop in oxygen levels, that some airlines are considering ways to increase the pressure on flights. In fact, Boeing designed its new 787 Dreamliner so that it can be pressurized to the equivalent of lower altitudes for this reason, according to the researchers.
“But although passengers may feel better with higher pressurized cabins during flights,” the researchers say, “they may lose the potential advantage of recovering from jet lag.”