Scientists find drinking alcohol on a long-haul flight could be bad for sleeping passengers’ hearts

An alcoholic drink on a plane.

There could be a risk to sleeping passengers’ heart health if they consume alcohol on a long-haul flight, researchers have warned.

In a new study published in the journal Thorax, a monthly peer-reviewed publication by the British Medical Journal (BMJ), German researchers found that drinking alcohol while on a flight could decrease blood oxygen levels and increase the heart rate during sleep.

They analysed the oxygen levels in the blood of 48 healthy participants aged 18 to 40 who were randomly split into two groups.

One group spent two nights in a sleep laboratory, while the other was put in an altitude chamber that corresponded to roughly 2,438 metres above sea level, reflecting cabin pressure on a commercial flight.

Participants consumed alcohol before one of the nights and had two eight-hour recovery nights in between.

Those exposed to a combination of cabin pressure and alcohol had their blood oxygen levels decrease to a median of 85 per cent during sleep. Their heart rates increased to a median 87.7 beats per minute (bpm).

This compared to 88 per cent blood oxygen level and 72.9 bpm for those experiencing cabin pressure without consuming alcohol.

For the group in a sleep laboratory that did not drink, the median blood oxygen level was 95.8 per cent with a heart rate of 63.7 bpm.

“We expected that the combination of alcohol, sleep, and hypobaric hypoxia [low oxygen at high altitute] would decrease the oxygen saturation. But we were surprised to see that the effect was so strong,” Eva-Maria Elmenhorst, one of the study authors from the German Aerospace Center’s Institute of Aerospace Medicine, told Euronews Health.

Elmenhorst added that they included only young and healthy participants and still saw “desaturations of extended duration”.

“Translated to the situation on a plane, we think that especially passengers with pre-existing medical conditions might be at risk. Their oxygen saturation might be low to begin with and then drop to even lower levels,” she said.

This could lead to inflight medical emergencies, she added.

As the small study only included healthy individuals, it does not represent the average population, researchers qualified. The sleeping conditions also resembled business or first class more than economy as participants slept horizontally.

The researchers worked to create a realistic simulation of a long-haul flight, with pressure similar to that found in an airplane cabin and inflight noise they recorded at cruising altitude.

Participants drank the amount of alcohol needed to reach 0.06 per cent blood alcohol concentration, similar to typical driving limits in the West.

The participants drank roughly the equivalent of two cans of beer or two glasses of wine, the authors said, with a mean blood alcohol concentration of 0.043 per cent.

Researchers examined four participants at a time so the “passengers” had limited space (like on a plane) and they limited sleep to four hours, resembling undisturbed time on a long-haul flight.

Elmenhorst says her main recommendation after the study is that passengers “should be made aware that drinking alcohol during a flight is not without risk”.