What is it and can you prevent it?


After almost a century of intercontinental journey you would possibly suppose we’d have gotten on prime of jet lag. But regardless of many inventions on this space, there’s nonetheless so much we don’t find out about this contemporary journey dysfunction.

In 2022, greater than 5.2 million Australians took abroad journeys. Some could have been impacted by jet lag, to larger or lesser levels; and the results of poor efficiency again at work could have been felt by companies and governments. As anybody who has jetted throughout time zones will know, the foggy head, insomnia and/or sleepiness is finest prevented, if it may be.

What actually is jet lag, although, and may you dodge it – or, at the least, reduce the results?

Credit score:Picture: Getty Photographs. Paintings: Aresna Villanueva

What’s jet lag (and what’s a circadian rhythm)?

Also referred to as jet lag dysfunction or the far much less catchy “time zone change syndrome”, jet lag is a brief sleep drawback brought on by fast journey over a number of time zones. Our physique’s inner clock, or circadian rhythms, get out of sync with the light-dark (sleep-wake) cycle round us.

The primary circadian timekeeper in our our bodies is within the mind – within the suprachiasmatic nucleus within the hypothalamus. It messages the physique to supply hormones controlling on a regular basis capabilities, from urge for food and sleep to alertness and temperature. This timekeeper responds to gentle and meal timings, and permits our physique to function at peak effectivity always.

With the Earth rotating on its axis relative to the solar in a 24-hour cycle, we comply with the cycle too (most individuals’s cycle is definitely ever so barely longer than 24 hours). Circadian is Latin for “a couple of day”. This isn’t distinctive to people. Nearly all organisms use circadian clocks to anticipate modifications within the atmosphere; a fungus will use circadian gentle cues to supply carotenoids within the hours after dawn to fend off ultraviolet radiation, a flower will open at dawn and emit a scent to draw pollinating bugs, finally closing at sundown.

It’s estimated to take a couple of full day to regulate for each hour of time zone modifications.

So, once we change time zones, there’s a mismatch between our physique’s clock and the exterior cues it’s responding to – and the disconnect triggers modifications in our our bodies. The severity of the jet lag is worse the extra time zones crossed – with none intervention, it’s estimated to take a couple of full day to regulate for each hour of time zone modifications. To place that in perspective, that bucket record journey from Sydney to Paris could also be blighted with jet lag signs for the primary eight days. The result’s all too acquainted: fatigue, insomnia, headache, irritability, digestive points, poor focus, reminiscence lapses – even impaired judgement and decision-making.

The hypothalamus is the part of the brain that regulates our circadian rhythms.

The hypothalamus is the a part of the mind that regulates our circadian rhythms.Credit score:Getty Photographs

Do some folks expertise jet lag greater than others?

Sure, however we don’t actually know why. We all know that as many as three-quarters of individuals have a circadian rhythm that’s a bit longer than 24 hours and, with out exterior cues, their sleep time would drift later and later every day.

It does appear that individuals’s pure sleep desire, often known as their chronotype, performs an element. An evening owl will discover it simpler to “section delay” (that’s, delay their circadian rhythm) when travelling westward greater than a morning lark as heading west requires staying awake for longer (as a result of they’ve gone again in time zones).

Travelling east requires section advance; and it’s simpler to increase a wake cycle by staying up later than it’s to pressure sleep whenever you’re not drained. Thus the saying “west is finest”. “We expect that [night owls] would have a tougher time coming again and adapting to eastward journey as a result of that requires their physique clock to go in the other way, so to go to mattress earlier,” says Dr Yu Solar Bin, an epidemiologist and circadian rhythm researcher on the College of Sydney.


A Monash College 2019 examine revealed within the journal Sleep Drugs discovered night time owl individuals had been capable of shift their sleep/wake cycle ahead by two hours by waking earlier, maximising outside gentle publicity, then sleeping earlier and limiting gentle publicity within the night. Meal timings had been additionally used to shift the physique clock; breakfast quickly after waking and dinner earlier than 7pm.

Whereas there isn’t analysis round gender variations in jet lag, age could also be an element. “Among the age distinction may be as a consequence of this concept of a morning versus night varieties,” says Dr Bin, “as a result of usually as folks become older they turn out to be extra morning oriented, so they could really discover it simpler to cope with eastward journey.”

How unhealthy is jet lag on your well being?

We all know sleep – and getting the correct amount – is necessary, even should you issue out whizzing throughout time zones. Poor sleep habits, together with daytime dozing, was related to impaired mind well being and decrease mind volumes in a single latest examine by the Australian Nationwide College, which regarded on the sleep habits of greater than 29,000 folks aged between 37 and 73. “Getting greater than 9 hours of sleep a day or lower than six hours had been each related to decrease mind quantity and cognitive measures – essential for issues like response time and reminiscence,” mentioned lead writer Dr Tergel Namsrai.

A College of Sydney examine of greater than 300,000 middle-aged adults discovered a hyperlink between poor sleep and heart problems and untimely demise.

And a latest large-scale Flinders College examine into the results of variable sleep patterns on blood strain discovered a robust correlation between elevated hypertension and irregular sleep period and timing. “These findings illustrate how irregularity in each period and timing of sleep onset and waking up is a transparent threat marker for poor cardiovascular well being, together with the full variety of hours we sleep,” mentioned co-author Dr Bastien Lechat.

Whereas jet lag is a brief sleep problem, the proof across the hostile well being results of shift work and the disruption to circadian cycles raises questions for frequent flyers similar to enterprise travellers and airline crew. (Even the short-term results may be a trigger for concern, say, in case your job depends on being alert.)

In 2022, Ethiopian Airways flight ET343 was en route from Khartoum to Addis Ababa when each pilots fell asleep within the cockpit. Air-traffic controllers did not get their consideration because the plane cruised previous the runway at 37,000 toes, with the duo waking solely after the autopilot disconnected and an alarm sounded. The pilots, who had been each affected by “pilot fatigue”, safely landed the plane 25 minutes later.

Whereas such circumstances make for sensational information headlines, severe business plane incidents or accidents – crashes or pilots falling asleep on the controls – are extraordinarily uncommon. Regulatory authorities recognise the significance of fatigue administration in aviation security: the Australian Civil Aviation Security Authority units flight-time limits for pilots (between 10 and 12 hours) in addition to minimal sleep alternatives (eight hours) and off-duty intervals (12 hours), amongst different security measures. Nonetheless, pilot fatigue stays a priority throughout the business.

“Circadian misalignment … in addition to the sleep loss … have a major influence on efficiency.”

“You don’t have to Google very far to search out stories of fatigue-related accidents in any business, and significantly aviation,” says Dr Tracey Sletten, a shift work and fatigue knowledgeable with Monash College. “We all know that the circadian misalignment that we expertise with jet lag, in addition to the sleep loss as a result of we’re making an attempt to sleep at a time that our physique doesn’t wish to sleep, have a major influence on efficiency,” she says.

A latest overview on the influence of worldwide flight operations on cabin crew discovered a excessive prevalence of fatigue, poor sleep high quality, threat of sleep issues and psychological well being points. Senior writer Professor Amy Jordan says cabin crew typically resort to non-beneficial methods to deal with the jet lag. “There was a really excessive use of caffeine to stay awake, and alcohol to help sleep,” says Jordan, who added that consuming caffeine and alcohol was typically at ranges and occasions that might really impair an individual’s sleep. The analysis indicated extra coaching and assist is required for cabin crew in comparison with pilots.

Do melatonin or sleeping drugs assist?

Melatonin is a hormone produced in our pineal gland that makes us sleepy earlier than bedtime. It may be taken in an artificial capsule, liquid and chewable kind to assist cut back the results of jet lag.

“From my viewpoint, melatonin might be the go-to when it comes to its capacity to section shift [circadian rhythm],” mentioned Dr Janet Cheung, a pharmacist and sleep treatment knowledgeable on the College of Sydney. “[Sleeping pills] assist with sleep promotion however once we’re speaking about jet lag the difficulty is the dyssynchrony, so a misalignment between your physique’s inner physique clock versus the exterior environments. If we wish to deal with jet lag then we’ve got to deal with that underlying physiology.”

Swiss International Air Lines’ new cabin design with anti-jet lag lighting.

Swiss Worldwide Air Traces’ new cabin design with anti-jet lag lighting.

In Australia, melatonin is accessible by prescription solely, or with out to these aged over 55 with insomnia, with analysis exhibiting it’s efficient within the remedy of jet lag when taken an hour or two earlier than sleeping. The Therapeutic Items Administration (TGA) is seeking to amend the scheduling of melatonin for non-prescription use in jet lag administration.

There’s inconclusive proof when it comes to its long-term use, although, “as a result of we haven’t performed lots of research”, says Cheung. And one overview of the proof round melatonin discovered that it was “removed from a silver bullet” for jet lag and raised considerations over an absence of evaluation of potential side-effects (similar to extra frequent seizures in folks with epilepsy). It’s additionally not advisable for these with autoimmune ailments.

Is there anything we are able to do to scale back jet lag?

For those who suppose making an attempt to regulate to a vacation spot three time zones away is difficult, attempt coping with a brand new dawn and sundown each hour-and-a-half because the astronauts typically do. House journey has helped set up a blueprint for managing our physique clocks.

“Astronauts don’t actually expertise jet lag however they do expertise a type of circadian misalignment,” says Dr Erin Flynn-Evans, director of the NASA Ames Analysis Middle’s Fatigue Countermeasures Laboratory. “In low-Earth orbit, similar to on the Worldwide House Station, astronauts circle the Earth each 90 minutes. This implies they expertise about 45 minutes of sunshine and 45 minutes of darkish again and again. It’s not doable for people to adapt to such a brief light-dark cycle to allow them to turn out to be circadian misaligned.”

Smart light therapy glasses designed to help shift your body.

Good gentle remedy glasses designed to assist shift your physique.

Darkened sleeping quarters and enhanced inside lighting throughout wakeful time have helped astronauts keep aligned to one thing approaching a 24-hour schedule. However regardless of the terribly high-tech nature of the area program, Flynn-Evans’ lab has discovered old style wholesome sleep practices work finest. “These embody an optimised sleep atmosphere, ample daytime lighting and an everyday schedule,” she says. “These could appear a bit boring however they work.”

Lie-flat seats and cozy airline PJs are, sadly, not the usual in long-haul air journey however there are nonetheless methods to offset jet lag within the cabin (though analysis exhibits travellers could be their very own worst enemies; Qantas and the College of Sydney’s Charles Perkins Centre have discovered that most passengers keep away from the best methods for decreasing jet lag similar to getting daylight on the vacation spot and avoiding alcohol).

Cabin lighting is more and more taking part in a job for airways similar to Qantas and Swiss Worldwide on lengthy hauls. Researchers from the Charles Perkins Centre are hoping to finetune Qantas’s onboard program by 2024 utilizing knowledge on the body-clock timing of pilots and cabin crew collected over a sequence of take a look at flights.

“You may really use units like that that will help you to shift your physique clock.”

There are additionally gentle remedy wearable glasses and transportable gentle bins that stream gentle of varied intensities that will help you make the circadian shift extra quickly – although it’s price noting your common units might maybe do the trick. “It’s all in regards to the depth of sunshine you get in your eye, and that’s an issue for individuals who take their telephones and units to mattress and flood themselves with melatonin-suppressing gentle,” says Dr Bin. “That has tended to make us all begin sleeping later than up to now however, on this context of journey, you may really use units like that that will help you to shift your physique clock.”

Dietitian Melissa Adamski advises consuming smaller meals, and avoiding extremely processed meals, whilst you regulate to new time zones.

In the meantime, jet lag apps and on-line calculators can tailor packages that set you up for one more time zone – you begin a few days earlier than boarding your flight, nudging your physique clock in the suitable route. A former NASA astronaut of 18 years, Mike Massimino, helped co-develop an app with recommendation marked on a calendar hour by hour: when to attempt to sleep in a darkish atmosphere, when to attempt for a light-weight nap, when to keep away from caffeine and when to drink it, should you do, in addition to when to ditch sun shades and get no matter gentle publicity, indoors or out, you may.


Some consultants do it themselves. “I arrange a jet lag plan for myself any time I journey and successfully eradicate jet lag,” says Sletten. “I’ve seen how nicely it really works.” The fatigue knowledgeable’s plan includes following a roster of particularly timed gentle publicity remedy periods, in accordance with the native time at her vacation spot. “I would begin staying up later at residence, giving myself gentle publicity within the night to push the physique clock again later, and dimming my gentle within the morning,” Sletten says. “I’ll have shifted my physique clock a number of time zones earlier than I’ve even gotten on the airplane.”

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