A flight attendant has revealed just how much water your body loses during a flight, and it’s a lot.
It’s easy to forget to drink water mid-air especially during a long-haul journey.
Mostly you’re just trying to kill time – whether it be (attempting) to sleep, watching a movie or chatting away with your mate.
Some passengers also tend to get a bit excited and knock back a couple of wines before realising they’ve gone hours without sipping an ounce of water.
Dehydration is common on long-haul flights. It can explain why your throat, nose and skin can feel dry on a plane – and generally, the longer the flight, the greater the risk of dehydration.
Ben Whatman, in-flight services manager for Air New Zealand, explains why it’s important to keep hydrated.
“During a long-haul flight, the key thing is to feel comfortable and safe, especially when you’re wanting to get that much-needed shut-eye in an over 10-hour flight,” he told news.com.au.
“Due to the recirculated air on a plane, your throat, nose and skin will tend to get dry – in fact you could lose up to 1.5 to 2 litres of water in a 10-hour flight.”
To ensure you’re not dried out, Mr Whatman recommends drinking water before you board your flight, as well as consistently during it.
There are low levels of humidity in the cabin compared with what you’d expect on the ground – this is mostly because a lot of the air circulating through the cabin is drawn from the outside, and there’s not a lot of moisture in the air at high altitudes, CNN reports.
As such, the Aerospace Medical Association (AsMA) recommends drinking a cup of water per hour while on a flight.
“Humidity in the cabin is usually low: in the range of 20 per cent,” it states. “There is no specific risk to your health, but low humidity can cause mild discomfort, particularly
dry skin and eye irritation for sensitive people.”
AsMA also recommends to limit consumption of alcohol, tea, coffee and caffeinated drinks “because they cause you to lose fluids”.
Meanwhile, it explained that the body contains air in the middle ear (inside of the ear drum) and sinuses.
“As the aircraft ascends, the air in these cavities will expand but the excess pressure will be released outside via tubes connecting them to the nose.”
“On descent the reverse occurs, with air flowing from outside to these cavities via the same tubes. This is well-tolerated as long as the air can flow into and out of these cavities freely. “To facilitate the free flow of air, particularly on descent, it is helpful to periodically swallow, chew or yawn.”
CNN reported that low levels of humidity in the cabin is because a lot of the air circulating through the cabin is drawn from the outside, and there’s not a lot of moisture in the air at high altitudes.
“You also risk dehydration by not drinking enough water, or drinking too much alcohol (alcohol is a diuretic, resulting in an increase in fluid lost),” it explained.
According to O. R. S Hydration, there is lower pressure inside the cabin than at sea level.
“Something few people know about is that low pressure will cause less oxygen to be absorbed by your blood,” it explains.
It added that if you don’t hydrate your body often, other things can happen such as your body finding it hard to regulate its core temperature.
“Second, you will experience low blood pressure (due to a lower volume of blood).”
It also added your body can then start feeling tired, cranky and lethargic.
“Water is a fundamental component of glycogen, a glucose storage facility for our muscles,” it explained.
“After several hours without water, you’ll find even walking to the toilet a struggle.”
It’s also why passengers need to move around the cabin and while a plane may not be the easiest place to hit your daily step count, it’s important to try.
“When you’re crammed into a tiny airplane seat, your body has a hard time pumping blood from your legs back to your heart to keep it circulating,” Dr Aaron Aday, a cardiology fellow at Brigham and Women’s Hospital in Boston told CN Traveler.
“On the flip side, when you’re walking around, your calf muscles effectively work to pump blood back up to your heart.”
If you don’t want to constantly annoy the person sitting next to you, Dr Aday recommends doing this at your seat – flexing and relaxing your calf muscles and feet, rolling your ankles; and clenching and spreading out your toes.
There’s no research that spells out just how much time you need to spend moving around to cut your risk of deep vein thrombosis (DVT), but Dr Aday suggests strolling the aisles once an hour, adding “most people feel better doing that anyway”.
It’s important to follow the advice the airlines give you, and see your doctor before you travel if necessary.
But, as advised, just try and move around the cabin and drinks lots of water.