Booze could threaten a sleeping air passenger’s heart health, particularly on long-haul flights, a new study warns.

Alcohol combined with cabin pressure at cruising altitude lowers the amount of oxygen in the blood and raises the heart rate for a long period, even in the young and healthy, researchers explained.

And the more alcohol a person drinks, the greater these effects might be – especially among older passengers or those with chronic health problems, results show.

Blood oxygen levels can decline to around 90% in healthy passengers at cruising altitude, researchers said in background notes. Anything lower than that is considered hypobaric hypoxia, or low blood oxygen levels at high altitude.

Alcohol relaxes blood vessel walls and increases heart rate during sleep, causing an effect similar to hypobaric hypoxia, researchers said. That made them suspect the combination could do harm to sleeping air passengers.

For their experiment, researchers recruited 48 people ages 18 to 40. They assigned half to a sleep lab under normal air pressure and half to an altitude chamber that mimicked cabin pressure at cruising altitude.

Among those, half were asked to drink an amount of vodka that roughly equaled two cans of beer or two glasses of wine.

The combination of alcohol and cabin pressure caused a fall in blood oxygen levels to just over 85%, and a compensatory increase in heart rate to an average 88 beats per minute while sleeping, results show.

By comparison, those in the altitude chamber who hadn’t drunk any alcohol had just over 88% blood oxygen and a heart rate just under 73 beats per minute.

Meanwhile, those in the sleep lab who drank alcohol had just under 95% blood oxygen and just under 77 beats per minute heart rate, while it was just under 96% blood oxygen and just under 64 beats per minute for those who hadn’t had alcohol.

Oxygen levels below the healthy norm lasted for 201 minutes with alcohol consumption and cabin pressure, compared with 173 minutes without alcohol under cabin pressure.

The new study was published June 3 in the journal Thorax.

“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,” concluded the team led by senior researcher Eva-Maria Elmhorst, deputy head of sleep research with the German Institute of Aerospace Medicine at Aachen University.

“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,” they added.

More information

Northwestern Medicine has more about healthy plane travel.

SOURCE: BMJ, news release, June 3, 2024