Staying Healthy on Long-Haul Flights

Travel Editorial Team Staff Writer · Feb 18, 2024 · 6 min read

Photo: AscendWit.com | Explore Engaging Blogs. editorial

Cabin pressure, dry air, and limited movement can all affect how you feel on arrival. Here's how to give your body a fair chance.

Key Takeaways

Cabin air is significantly drier than normal indoor environments, making regular hydration essential.
Sitting still for hours raises the risk of deep vein thrombosis — movement and circulation exercises help counter this.
Jet lag and sleep disruption are worsened by alcohol, caffeine, and bright screen light before sleeping onboard.
Light, familiar foods and avoiding overeating can reduce digestive discomfort at altitude.
A few deliberate habits before, during, and after a long flight significantly affect how you feel on arrival.

Why Long-Haul Flights Are Hard on the Body

A flight lasting eight or more hours puts your body in an environment it wasn't built for. Cabin pressure is typically maintained at the equivalent of 6,000–8,000 feet above sea level — lower than sea level, but still enough to reduce the oxygen concentration in your blood slightly and cause mild altitude effects in some people. Combined with humidity levels that can drop below 20% (far drier than most homes or offices), the result is a recipe for dehydration, fatigue, and general discomfort.

Add limited mobility, disrupted sleep, and a shifted time zone, and it's easy to understand why many travelers arrive feeling rough. The good news: most of these effects are manageable with preparation and a few smart onboard habits. Understanding what's actually happening to your body is the first step. For more on how flying compares with other long-distance options, see our comparison of road trips vs. flying.

Best Practices for Staying Healthy in the Air

The following practices address the most common physical stressors of long-haul travel. None require special equipment — just awareness and a little planning.

Drink water consistently throughout the flight, not just when you feel thirsty.

Cabin humidity is far lower than typical indoor air, and thirst is a lagging indicator — by the time you feel it, you're already mildly dehydrated. Dehydration contributes to headaches, fatigue, and difficulty concentrating, all common complaints after long flights.

Example: A traveler on a 12-hour flight aims for roughly one cup of water per hour and brings an empty refillable bottle to fill at the gate, avoiding dependence on infrequent beverage service.

Move your legs and do simple circulation exercises every 60–90 minutes.

Prolonged sitting slows blood flow in the lower legs, increasing the risk of deep vein thrombosis (DVT) — blood clots that can form in deep veins. People with certain risk factors are more vulnerable, but brief movement benefits nearly all travelers on extended flights.

Example: Every hour and a half, a passenger stands, walks to the back of the plane, and spends two minutes doing calf raises and ankle circles before returning to their seat.

Eat light, familiar meals and avoid overeating at altitude.

Reduced cabin pressure causes gas to expand in the digestive tract, making overeating or gas-producing foods more uncomfortable at altitude. Digestion also slows during long periods of inactivity, so large, rich meals can cause bloating and sluggishness.

Example: A traveler skips the second bread roll and salty processed snacks, opting for the lighter meal option and a small amount of whatever fruit is available.

Limit alcohol and caffeine, especially during the second half of the flight.

Both alcohol and caffeine are diuretics that accelerate fluid loss — worsening dehydration in an already dry cabin. Alcohol also disrupts sleep architecture, meaning even a short rest after drinking will feel less restorative.

Example: On an overnight transatlantic flight, a passenger has one glass of wine with dinner but switches to water once the cabin lights dim and the sleep window begins.

Moisturize skin and use lubricating eye drops if you wear contact lenses.

Dry cabin air pulls moisture from exposed skin and eyes. Contact lens wearers are especially susceptible to eye irritation and redness at altitude, and dry, cracked skin around the nose and mouth is a common post-flight complaint.

Example: A traveler packs a travel-sized facial moisturizer in their carry-on and switches to glasses for the second half of a 14-hour flight to give their eyes a break.

Dress in loose, comfortable layers and wear compression socks on very long flights.

Compression socks apply gentle graduated pressure to the lower legs, helping maintain blood flow and reducing swelling in the feet and ankles — a common occurrence during extended sitting. Loose clothing reduces pressure on the abdomen and improves comfort overall.

Example: A traveler with a tendency toward ankle swelling puts on knee-high compression socks before boarding and removes them only after the flight, noting significantly less puffiness on arrival.

Quick Actions You Can Take Right Now

Whether your flight is tomorrow or next month, these are the highest-impact steps you can take immediately to prepare your body for a long journey.

high Fill a refillable water bottle before boarding and place it in the seat pocket in front of you as a constant reminder to drink.

high Set a phone alarm or watch timer to go off every 90 minutes as a movement reminder during the flight.

medium Pack a small pouch in your personal item with lip balm, facial moisturizer, and if needed, lubricating eye drops.

medium Choose your seat thoughtfully — an aisle seat makes it far easier to stand and move without disturbing other passengers.

Book a Pre-Flight Night That Prioritizes Sleep

Starting a long-haul flight already sleep-deprived makes everything harder — your body's ability to regulate temperature, fight off germs, and adjust to a new time zone all depend on adequate rest. Where possible, avoid scheduling early-morning departures that require a 3 a.m. alarm. If your departure time is fixed, plan the days before your trip to bank as much sleep as your schedule allows.

Arriving well-rested is also much easier when your itinerary isn't overloaded from day one. Our guide to building an itinerary that doesn't leave you exhausted walks through how to pace your schedule once you land.

Managing Sleep, Light, and Jet Lag

Sleep disruption is one of the most complained-about aspects of long-haul travel, and it's closely tied to jet lag — the mismatch between your internal body clock and the local time at your destination. While jet lag can't be completely avoided on very long flights, its severity is meaningfully influenced by choices you make during the flight.

“Light is the most powerful cue for resetting the human circadian clock. Managing your light exposure strategically — both during the flight and in the first days at your destination — is one of the most effective tools you have against jet lag.”

— Till Roenneberg, Chronobiologist and professor at Ludwig Maximilian University of Munich, known for research on circadian rhythms and social jet lag

Dim your screen and reduce exposure to bright overhead lights in the hours before your planned sleep window on the plane. If crossing multiple time zones westward, try to stay awake as long as possible; eastward, aim to sleep earlier. Avoid alcohol as a sleep aid — it fragments sleep quality even if it helps you fall asleep faster. For a deeper look at this topic, our article on what actually helps with jet lag separates folklore from research-backed strategies.

This article provides general travel health information for educational purposes only. It is not a substitute for advice from a qualified healthcare professional. If you have existing health conditions — including cardiovascular concerns, blood clot history, or respiratory issues — consult your doctor before long-haul travel.

Travel Editorial Team

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