Those weird things that happen to your body on a plane, explained.

Regardless of how frequently you fly, air travel is full of surprises.

Some of these surprises are happy ones — scoring the exit row or an extra serve of dessert, for example. Others are not so welcome (oh hi, unexpected turbulence!).

Then there’s a whole other category of unexpected occurrences that would be better described as bizarre, if not a little embarrassing. From heightened emotions to flatulence, here are four common ways flying can mess with you, and why it happens.

Mile-high emotions

Even the steeliest of hearts have found themselves ugly-crying over a mediocre movie or drawn in a private spiral of contemplation/melancholia as soon as the wheels come off the tarmac.

While she isn’t aware of any scientific studies into the issue, Tal Schlosser, Clinical Psychologist and Director of My Life Psychologists, has some theories as to why people find their emotions heightened mid-flight. One is the separation from our regular busy lives.

“Sitting down on a flight is a rare moment of stillness for a lot of people, when they let themselves simply ‘sit’ with what they’re thinking or feeling without the distractions of their phone or regular activities,” she explains.

Another potential factor is the strong feelings that can be triggered by travel — whether it be sadness at leaving someone behind, or excitement about a big adventure. Schlosser suggests this can “prime” some people into feeling more emotional.

“In addition, we often give ourselves a ‘free pass’ when on flights and this could also make us more vulnerable to becoming emotional. For example, we give ourselves permission to read more lightweight ‘aeroplane novels’ or watch trashy movies,” she adds.

Yeah, it's pretty common to get emotional on a plane. (Image: Universal Pictures)

The physical aspect of flying might also come into play. "For an extended period of time you're stuck in a confined space surrounded by strangers in very close proximity to you who are observing you in all your vulnerability, like sleeping, eating, and not looking as groomed as usual," Schlosser says.

"Fatigue and disrupted sleep may also contribute to making passengers more emotionally vulnerable, and perhaps even the lower oxygen levels."

Writer Brett Martin has an interesting theory of his own. In a 2011 episode of This American Life, Martin argued that as plane passengers, we're forced to relinquish all control — and the effect is infantilising.

"You’re strapped in, given a blanket, a sippy cup, and tiny silverware, forced to do what you’re told and borne away at speeds we can’t conceive, without seeing where we’re going,” he explained. If that's not enough to make you feel vulnerable, what will?

Breaking out

Greasy hair, under-eye luggage... yeah, nobody feels particularly fresh-faced after a long haul flight. And those mile-high breakouts don't really help matters.

Dermatologist Dr Adam Sheridan says several aspects of air travel can directly impact your skin. These include "recirculated air, reduced water quality, immobility, and potential contact with viruses and bacteria through inhalation and contact with shared surfaces," he explains. Great.

There are also indirect impacts, including hormonal changes (blame your stress, excitement and sleep deprication), changes to diet, the departure from your regular skincare regimen, and more increased unconscious face touching.

"This tends to occur during periods of prolonged travel seated in one position and with boredom," Dr Sheridan says.

Sure, give yourself an on-board facial. Why not? (Image: Etihad Airways)

Fortunately, there are some preventative steps that will keep your jet-setting skin happy. Dr Sheridan recommends showering, moisturising and eating well as close to your departure time as possible, and trying to embark in a rested state to cut down on stress.

Taking some travel-size skincare on-board can also help.

"A gentle cleanser, simple moisturiser and SPF 50+ non-greasy sunscreen are essentials. Keep thick make up and concealers to a minimum. Although these help you board looking like a rock star, you may disembark in a less glamourous state with congested flaky and dull skin," Dr Sheridan says.

"Try to maintain a healthy diet and adequate clear fluid intake throughout the flight and understand that recirculated air means you will 'dry out' faster than when on the ground. If possible, resist the lure of the free alcohol as this accelerates your trajectory towards dehydration."

The dreaded Plane Cold

Nothing screams 'happy holiday' like spending 27 hours in the air, only to arrive at your destination with a fresh cold (and neck pains from falling asleep in a weird position).

Researchers have explored a number of theories as to why extended time in plane cabins can give us the sniffles. Food, water, alcohol consumption and air quality have all been analysed, but it seems lack of moisture is the most likely culprit.

“At normal flying altitude the air can be as dry as 10 per cent or more than being at normal ground level. Dry air is known to adversely affect the lining of our nose and throat and makes them more prone to infection,” explains Dr Piraveen Pirakalathanan, Principal Medical Officer of Healthand. (Post continues after gallery.)

 There's also the unpleasant fact that bacteria and viruses can survive for several hours in even the cleanest cabins.

“The toilet is a common place to catch infections, but other surfaces can include tray tables, pillows, blankets and even the magazines you might read in back pocket of a seat,” Dr Pirakalathanan says.

Finally, the physically exhausting effect of long-haul flights — stopovers at odd times, crossing timezones, interrupted sleep — makes your body more susceptible to illness.

To save yourself the misery, Dr Pirakalathanan recommends picking the window seat, as the aisle seat is more likely to be contaminated by passengers walking past (i.e. to and from the toilet). Keeping your fluids up, taking hand sanitiser on board, and using your own pillows and blankets if possible can also help. Good luck up there.

The flatulence thing

Well, here's something the on-board safety card doesn't prepare you for: air travel increases flatulence.

This was established in a 2013 study published in the New Zealand Medical Journal, so take comfort in the fact that it's not just you. Even pilots experience it.

Lead author Dr Jacob Rosenberg decided to investigate the "mechanisms of increased bowel air volume" while flying, after noticing an almost-smashed drink bottle in his cabin bag following a flight.

Watch: Cabin crew anonymously share airline secrets. Prepare to cringe. (Post continues after video.)

 Essentially, he found that the volume of a passenger's intestinal gasses changes as the cabin pressure does.

"When altitude increases, pressure decreases. According to the thermodynamic principal known as the 'ideal gas law,' as pressure drops, volume increases. While cabins are pressurised to compensate, the mechanisms can only do so much," NBC reports.

A plane is probably the last place you want to break wind, being a confined space and all, but it's probably wiser to do so. Holding it in can lead to "discomfort and even pain, bloating, dyspepsia and pyrosis," the study authors note.

Hey, how's that for a way to open the conversation with your seat buddy?

What weird effect does flying have on your body?