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The Hidden Risks of Drinking Alcohol During Long Flights

How drinking in the air can lower oxygen levels, stress your heart, and disrupt sleep.

That glass of wine or beer you sip before dozing off on a long-haul flight might do more harm than you think. New research suggests that alcohol can significantly lower blood oxygen levels, increase heart rate, and reduce sleep quality especially at cruising altitude.

Alcohol + Altitude = Lower Oxygen and Faster Heart Rate

In a study simulating in-flight conditions, healthy young adults who drank the equivalent of two glasses of wine or beer before sleeping for four hours experienced:

  • Median blood oxygen levels dropping to 85% (healthy levels should be 95–100%)

  • Heart rate rising to 88 beats per minute

Anything below 92% oxygen saturation signals hypoxia, when the body isn’t getting enough oxygen at the tissue level. This can lead to symptoms such as shortness of breath, confusion, and rapid heartbeat. For passengers with heart or lung issues, the risk could be more serious—even life-threatening.

The Risks Are Higher in First or Business Class

Researchers simulated a supine sleeping position (lying down), typical in first and business class. Sleeping in this position at altitude led to greater oxygen drops compared to sitting upright, as in economy.
While the study focused on one moderate serving of alcohol, real-world passengers may drink more further increasing the effect.

Poor Sleep Quality, No Matter Where You Sit

Alcohol may make you fall asleep faster, but it reduces REM sleep (the restorative stage) and increases light, shallow sleep. Even without altitude effects, drinking before bed is linked to poorer sleep quality and more nighttime awakenings.

Flying Itself Stresses the Body

Airplane cabins are pressurized to an altitude of 7,500–8,000 feet similar to being in Aspen, Colorado. At this “thin air” level:

  • Blood vessels in the lungs constrict

  • Heart rate increases

  • Fluid shifts occur throughout the body

Humidity is also low, leading to faster dehydration, even if you don’t feel thirsty. Combine this with pre-flight stress, lack of rest, and alcohol’s diuretic effect, and you have a recipe for feeling worse during and after your trip.

Tips for Safer, Healthier Flights

If you want to feel better during and after a long-haul flight especially if you have underlying conditions skip the alcohol and try:

  • Drinking water before and during the flight

  • Eating a light, balanced meal before boarding

  • Moving and stretching regularly in your seat or the aisle

  • Wearing comfortable, non-restrictive clothing

  • Using eye masks or earplugs to help improve sleep without alcohol

Bottom line

Alcohol at altitude can lower oxygen levels, stress your heart, and worsen sleep. If you’re flying for many hours especially if you have heart or lung conditions your safest bet is to avoid alcohol until you land.

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