You already know what not to do on a plane if you don't want to be a giant jerk. (Exhibit A: Man watching iPad movie without headphones. Exhibit B: Woman eating pungent tuna wrap.)
But best practices can be less obvious for considerate humans who just want to make it from point A to point B safely. If you're one of these people, avoid these behaviors the next time you fly:
1. Sleeping through takeoff or landing. When the plane ascends or descends, the air pressure around you changes faster than the air inside your ears. If you've ever flown before, you know this can be super uncomfortable—but only temporarily. To equalize the pressure, all you need to do is chew gum; inhale, then exhale gently as you hold your mouth and nose shut; suck on candy; or yawn, according to MedlinePlus. In other words, you're better off awake. Accidentally sleep through the pressure change, and this condition will only get more uncomfortable, potentially instigating dizziness, ear infection, slight hearing loss, eardrum damage, or nosebleeds and severe hearing loss in the worst of cases.
2. Sitting from takeoff to landing. Low air pressure in the cabin can slow your circulation and set you up for blood clots, particularly in the legs. Sitting around doesn't help — especially if you're on birth control pills, because some can increase your risk of developing dangerous clots (even without air travel).
To reduce your risk of developing clots, which could pose major health issues if they travel to your lungs, brain, or heart, the CDC suggests getting up and moving around as often as possible. Of course that's easier said than done for lazies and people sitting in window or middle seats—it's all the more reason to choose an aisle seat when you can. Regardless of where you're seated, you can protect yourself by performing these exercises every so often (there aren't hard and fast guidelines on how frequently you should do them): Raise your heels while your toes are on the floor; raise your toes while your heels on the floor; and clench and release your leg muscles. Repeat each move a handful of times before moving on to the next, and repeat the entire series periodically throughout your flight. And if you zonk out on a red-eye? Just try to shift positions as often as possible, and move your legs anytime you're awake enough to think of it. (Some experts recommend against taking sleeping pills, lest they render you even more immobile.)
3. Dozing off when it's daytime at your final destination. Because this will make it harder to adjust to the time zone you're traveling to, it's a surefire way to screw yourself over. Instead, change your watch to reflect the time zone of wherever it is you're going as soon as you board the plane, recommends the National Sleep Foundation. Then adjust your activities accordingly: If your watch says it's bedtime, go ahead and shut your eyes. Otherwise, open up and face the day! (Even if it's dark out.)
4. Declining a beverage. Cabin air is notoriously dry. Because your body loses moisture every time you exhale, simply breathing at high altitudes can dehydrate you. So when the flight attendant rolls up, place an order and request refills on the regular.
5. Ordering tea or coffee. Never mind the fact that in-flight coffee is an insult to the beverage. Coffees and teas are made from plane tap water that could contain coliform, bacteria found in 12 percent of commercial airplanes, according to a 2012 Environmental Protection Agency report. As long as your immune system is up to snuff, the stuff won't necessarily make you sick. But because coliform comes from feces, where harmful bacteria also lurk, water that contains it is more likely to harbor scarier stuff like E. coli, which can really mess with your system. So don't risk it: Opt for bottled water, instead—and hold the ice if it's made with plane tap water. (Just ask an attendant.)
6. Drinking anything with bubbles. Changes in air pressure can cause gas in the body to expand as much as 25 percent, according to an Aerospace Medical Association report. Because bubbly beverages do the same thing, they can exacerbate these uncomfortable effects. Skip them to feel less bloated when you land.
7. Boozing it up. While alcohol might initially help you fall asleep on a flight, it can ultimately mess with your sleep quality, dehydrate you, and trigger a lingering hangover that makes you irritable and lethargic. Lay off the liquor until you're back on the ground to arrive on your A-game.
8. Bingeing on plane food. Of course you should eat when you're hungry—whether you're on a plane or elsewhere. But polish off all the inflight food just because you're bored, and you'll enjoy it less than you would on the ground: Dry cabin air and low air pressure can reduce your ability to perceive salty and sweet tastes by 15 to 30 percent— which can make foods taste worse when you eat it in the air, according to a German study. All the noise from the airplane engine doesn't help either, according to a Cornell University study that confirms the obvious: Environmental distractions can affect your sense of taste. Some airlines compensate for the ambiance by serving saltier foods, so you could end easily end up overdoing it on sodium.
9. Eating food after it falls on your tray table. When the Today show's investigative team swabbed random surfaces for germs during three different cross-country plane trips on separate airlines, guess where they found the highest levels of harmful bacteria, across the board? On plane tray tables. Flight attendants blame those passengers that use their trays as baby-changing tables. (And you know better than to eat off one of those.)
While ground crews are supposed to wipe down trays between flights, you never really know how well they get in there. Give the surface a once-over yourself using an antibacterial wipe, or hand sanitizer and a napkin. Skip this step, and you're better off sacrificing the peanut that graced your tray.
10. Fussing with your seat belt. The Today show investigators also found that seat belts were pretty icky—they, too, were covered with potentially harmful bacteria. While strapping in is obviously your only option and you should definitely do it, avoid touching the strap after you fasten it, and put your hand sanitizer to use after buckling in.
11. Walking around barefoot. Sure, it's nice to make yourself feel right at home inflight—particularly when you're in the air for hours or you fly overnight. However, former flight attendants say the floor can be positively filthy—and anyone with eyeballs can confirm that. Lurking trash and food debris should be reason enough to keep your shoes on—or at least slip them on for bathroom runs.
12. Holding it in until you get there. Unless you regularly relieve yourself in some hole in the woods, using the plane potty probably won't be the highlight of your trip. But if you feel the urge to pee while you're in the air, just suck it up and use the bathroom. Otherwise, your urine will hang around in the bladder where it can trigger an infection—and really make vacationing a pain.