The combination of alcohol and cabin pressure can be harmful to sleeping plane passengers’ heart health, a new study has found.
Drinking alcohol and then falling asleep on a plane may lower the amount of oxygen in the blood and raise your heart rate, even if you’re young and healthy — suggesting that consuming alcohol on planes may be a more dangerous choice than previously thought.
Knowing that alcohol increases heart rate during sleep and that cabin pressure at a high altitude causes a drop in blood oxygen saturation level, researchers set out to discover whether the combination of the two might have an additive effect on sleeping passengers.
The findings from their first-of-its-kind study were published earlier this month in Thorax.
While the cardiovascular effects were documented in young and healthy individuals, the authors said the impacts are likely more profound in older passengers and in those with pre-existing medical conditions.
The findings indicate that restricting alcohol access on long-haul flights may be a good idea, the researchers said.
The study process
To conduct the small study, researchers took 48 healthy participants between the ages of 18 and 40 and split them in half — assigning the first group to a sleep lab with normal ambient air pressure conditions (at sea level), and the other group to an altitude chamber that mimicked cabin pressure at cruising altitude (2438 m above sea level).
In each group, half of the participants drank alcohol and slept for four hours, while the other half slept for the same amount of time without consuming alcohol. All participants then had two recovery nights before swapping for one additional night.
The alcohol consisted of pure vodka that was equivalent to two cans of beer or two glasses of wine, consumed at 11:15 pm before sleeping — during which participants’ sleep cycle, blood oxygen levels, and heart rate were continuously monitored.
The results showed that alcohol and cabin pressure at cruising altitude led to an average fall of blood oxygen levels of just over 85%, and an average heart rate increase of nearly 88 beats/minute (bpm) during sleep. In comparison, no alcohol resulted in blood oxygen levels of just over 88% and a heart rate of just under 73 bpm.
Among participants in the sleep lab with normal air pressure conditions, those who drank alcohol had an average blood oxygen level of just under 95% and a heart rate of just under 77 bpm, while those who hadn’t drank had 96% and just under 64, respectively.
Blood oxygen levels are considered below the healthy clinical norm under 90%, and low levels lasted for 201 minutes with the combination of alcohol plus simulated cabin pressure at cruising altitude. Without alcohol, the period lasted 173 minutes. Under sleep lab conditions, it lasted for zero minutes with and without alcohol.
Alcohol and simulated cabin pressure at cruising altitude also reduced the duration of the deepest stage of the sleep cycle, N3, as did the duration of the REM sleep period.
The study is limited by its small sample size, the fact that the participants were all young and healthy and that all participants slept in the supine position — a luxury typically not afforded to passengers in economy class.
Still, the researchers say the findings are worth taking seriously.
“Together these results indicate that, even in young and healthy individuals, the combination of alcohol intake with sleeping under hypobaric conditions poses a considerable strain on the cardiac system and might lead to exacerbation of symptoms in patients with cardiac or pulmonary diseases,” the authors said. “Practitioners, passengers and crew should be informed about the potential risks, and it may be beneficial to consider altering regulations to restrict the access to alcoholic beverages on board aeroplanes.”
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