The combination of alcohol and cabin pressure at high altitude can reduce blood oxygen and increase heart rates in sleeping people.
- Drinking alcohol on an airplane, where the air pressure in the cabin drops, reduces the amount of oxygen in the blood and increases the heart rate, even in young, healthy people.
- Deepest sleep was reduced to 46.5 minutes under combined exposure to alcohol and simulated cabin pressure at aircraft altitude.
- “It might be beneficial to consider changing regulations to restrict access to alcoholic beverages on board aircraft,” the authors say.
Sleeping during a flight causes a decrease in blood oxygen, up to about 90%, caused by the decrease in atmospheric pressure in the cabin. Alcohol, which is frequently consumed by passengers on long-haul flights, relaxes the walls of blood vessels, thus increasing the heart rate during sleep. In a new study, researchers from the Institute of Aerospace Medicine (Germany) wanted to analyze the combined influence of alcohol and hypobaric hypoxia, i.e. the decrease in atmospheric air pressure with altitude, on sleep, blood oxygen saturation and heart rate.
An 85% drop in blood oxygen and more heartbeats per minute during sleep
For the purposes of the work published in the journal Thoraxthe scientists recruited 48 people aged 18 to 40 and randomly assigned them to two groups based on age, gender and body weight (BMI). Half of the participants were placed in a laboratory under normal ambient air pressure (sea level) and the other half in a room where the altitude mimicked the cabin pressure of an airplane (2,438 m above sea level). Twelve people in each group slept for four hours without drinking alcohol, while 12 slept for four hours after drinking alcohol for one night, followed by two nights of recovery, and then another night in which the process was reversed. The volunteers drank the equivalent of two cans of beer (5% alcohol) or two glasses of wine (175 ml, 12% alcohol). Their sleep cycle, blood oxygen saturation and heart rate were monitored continuously until four in the morning.
The results showed that the combined exposure to alcohol and hypobaric hypoxia decreased blood oxygen to a median of 85.32% and increased heart rate to a median of 87.73 beats per minute during sleep. In participants who had not drunk alcohol, the authors found that blood oxygen was 88.07% and heart rate was 72.90 beats per minute. Among those who had consumed alcohol and were in the laboratory where conditions were normal, the equivalent figures were just under 95% blood oxygen and just under 77 beats per minute heart rate, and for those who had not drunk alcohol, the figures were just under 96% oxygen and just under 64 beats per minute.
“Exacerbation of symptoms in patients with heart or lung disease”
“Oxygen levels below the healthy clinical norm (90%) lasted for 201 minutes with the combination of alcohol and simulated cabin pressure at aircraft altitude. This compares to a period of 173 minutes without alcohol and 0 minutes with and without alcohol under laboratory conditions,” can be read in the work. As for sleep, the deepest was reduced to 46.5 minutes under the combined exposure to alcohol and simulated cabin pressure at the altitude of an airplane, compared to the two laboratory conditions: after alcohol, 84 minutes and without alcohol, 67.5 minutes.
The scientists acknowledge the limitations of their research, including the small sample size and the fact that the volunteers were young and healthy. “They do not reflect the general population. Furthermore, the volunteers slept in a reclining position, a luxury usually reserved for those traveling in first class. The results may therefore not apply to the majority of airline passengers traveling in economy class. Nevertheless, the study shows that the combination of alcohol consumption and sleeping in hypobaric conditions puts considerable strain on the cardiac system and could lead to an exacerbation of symptoms in patients with heart or lung disease.”said the team.
These effects may be even greater in older people. “Cardiovascular symptoms have a prevalence of 7% of medical emergencies on aircraft, with cardiac arrest being the cause of 58% of diversions. (…) Practitioners, passengers and crew should be informed of the potential risks, and it may be beneficial to consider amending regulations to restrict access to alcoholic beverages on board aircraft.”
