While many find a little of bit of the bubbly helps make their flight more enjoyable, turns out a combination of alcohol and environmental flight changes may threaten the heart health of sleeping plane passengers, especially on long-haul flights, according to a study published in Thorax. The study aimed to determine if alcohol and cabin pressure together have an additive effect on sleeping passengers.
Researchers found that this duo reduces blood oxygen (SpO2) and raises the heart rate for a prolonged flight periods, even in young and healthy individuals. Higher alcohol consumption amplifies these effects, particularly among older passengers and those with pre-existing medical conditions.
At cruising altitude, atmospheric pressure drops, causing blood oxygen levels to fall to around 90% in healthy passengers. A further drop below this threshold is called hypobaric hypoxia. Alcohol relaxes blood vessels, increasing the heart rate during sleep, similarly to hypobaric hypoxia.
For the study, the investigators recruited 48 people aged 18-40, and were divided into two groups, with half sleeping under normal air pressure and half in an altitude chamber simulating cabin pressure at 2,438 meters. Each group had 12 people sleeping without alcohol and 12 with alcohol for one night, followed by recovery nights, then a reversal of conditions.
Participants drank the equivalent of 2 beers or 2 glasses of wine at 11:15 pm, and their sleep cycle, SpO2, and heart rate were monitored until 4 am.
The combination of alcohol and simulated cabin pressure reduced SpO2 to an average of just over 85% and increased heart rate to nearly 88 bpm during sleep, compared to just over 88% SpO2 and just under 73 bpm without alcohol at altitude. In the sleep lab, alcohol resulted in nearly 95% SpO2 and 77 bpm, and without alcohol, 96% SpO2 and 64 bpm.
Oxygen levels below the healthy norm lasted 201 minutes with both alcohol and cabin pressure, compared to 173 minutes without alcohol at altitude, and 0 minutes in the sleep lab.
Deep sleep (N3 stage) was reduced to 46.5 minutes with alcohol and cabin pressure, compared to 84 minutes with alcohol and 67.5 minutes without in the sleep lab. REM sleep was also shorter with both hypobaric hypoxia and alcohol.
They conclude that even young and healthy individuals experience significant cardiac strain from the combination of alcohol and low-pressure conditions, potentially worsening symptoms for those with cardiac or pulmonary diseases.
Despite feeling like things are similar inflight as it is when you’re sitting on the ground, the fact is that many physiological changes occur in response to the environmental changes up in the air. Flying is physiologically stressful and adding alcohol, a toxic substance that further stresses the body, will only compound the potential problems. Fly safe and refrain from alcohol before and during flight, there will be plenty of time to enjoy some bubbly after you land.
RA Trammer et al. Effects of moderate alcohol consumption and hypobaric hypoxia: implications for passengers’ sleep, oxygen saturation and heart rate on long-haul flights. Thorax (2024). https://doi.org/10.1136/thorax-2023-220998
