The ‘fasten seat belt’ sign is off, and the time for a nap on your flight is on.
You grab your neck pillow, eye mask and a glass of wine to make sure you are well-rested on the other side.
But that tactic isn’t such a good idea, according to new research.
Know the news with the 7NEWS app: Download today 
Airplane cabins are pressurised to maintain the equivalent of 2,438 metres of elevation, meaning the air pressure and oxygen levels are lower than what most people experience on Earth.
Combine that with alcohol consumption and sleep, and it’s more likely a person will experience an intensified drop in oxygen saturation in their blood, according to a study published on Monday in the journal Thorax.
“Please don’t drink alcohol on board of airplanes,” lead study author Dr Eva-Maria Elmenhorst said in an email.
Elmenhorst is the deputy of the department of sleep and human factors, and leader of the Working Group on Performance and Sleep, at the DLR Institute of Aerospace Medicine in Cologne, Germany.
To investigate, researchers created an atmospheric environment similar to an airplane cabin in flight.
Over two nights, 48 healthy adults slept for four hours in two different environments — once without alcohol and once after drinking the equivalent of two glasses of wine or cans of beer, according to the study.
On the nights with alcohol, researchers saw a lowered amount of oxygen and an increased heart rate, the study showed.
“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 researchers said.
The study is small.
But cardiologist Dr Andrew Freeman says it provides a starting point from which researchers should keep investigating the relationship between sleep, flight and alcohol.
Freeman, the director of cardiovascular prevention and wellness at National Jewish Health in Denver, was not involved in the research.
Many people may be drinking onboard to help them get to sleep in an often uncomfortable cabin — but doing so negatively impacts both long-term health and the immediate goal of getting some rest, experts said.
Alcohol gets you sleep — but not good sleep
The study authors didn’t just collect data on heart strain.
They also took a closer look at the participants’ quality of sleep. It wasn’t great.
Time in REM sleep — the rapid-eye movement stage that may be important to memory consolidation and brain recuperation — was shorter for people in the airplane conditions who had alcohol, the study showed.
The finding wasn’t a surprise, Freeman said.
Alcohol may help you get to sleep, but the quality isn’t as good as sleep while sober, he said.
“Many people have witnessed when people drink heavily, their snoring and the sleep apnea is much more severe,” Freeman said.
The quantity of sleep under the influence also tends to be different, said Dr Shalini Paruthi, adjunct professor at Saint Louis University School of Medicine.
People tend to get more fragmented sleep after drinking, meaning they wake up more in the night and tend not to sleep as long, said Paruthi, an American Academy of Sleep Medicine spokesperson. She was not involved in the research.
“Sometimes people will just think about the immediate effect of ‘Ooh it will make me fall asleep faster’ but they forget about all the other effects of the alcohol,” she said.
Be especially careful not to mix sleep aids with alcohol, because both are depressants and intensify their sedative effects when taken together, Freeman said.
“I’ve definitely seen … people taking sleeping pills combined with alcohol, which is a major issue,” he said.
“Then, there’s oftentimes a medical emergency.”
How to rest before your destination
If possible, try to keep to your natural body cycles when flying, Freeman said — although that might not always be possible.
That can look like choosing a flight that lines up with your sleep patterns so you can either land and just finish sleeping or land and start your day, he said.
Avoid creating those sleep and wake cycles with too many stimulants such as coffee or energy drinks and depressants like alcohol, he added.
Next, stay hydrated, because flying typically involves a dry environment and people don’t always hydrate properly, Freeman said.
The best thing to drink is water, he said.
Foods served at airports and airplanes can lean towards being salty, greasy and heavily processed.
So Freeman recommends either packing your own or finding airport options that are lighter and largely plant-based.
Exercise can also help you sleep better, so he advises avoiding elevators and travellators to get some steps in instead.
If you are on a long flight, try to get up and get some movement as well, Freeman said.
“The last thing I’ll point out is there’s lots of evidence that suggests that the blue lights that are emitted from screens and all that interfere with our sleep patterns,” he said.
“If you are trying to sleep on a plane, consider getting a noise-cancelling headphone and maybe not use your screens, especially while you’re waiting for the flight to take off.”
It may be harder to keep up your healthy habits on days when you fly, but making efforts to do so can help you arrive feeling good and ready for an adventure, Freeman said.
