Hochschild’s initial research focused on the airline industry, but it’s not just in-flight staff keeping up appearances. In fact, experts say emotional labour is a feature of nearly all occupations in which we interact with people, whether we work in a customer-facing role or not. The chances are, wherever you work, you spend a fair portion of your working day doing it.

When research into emotional labour first began, it focused on the service industry with the underlying presumption that the more client or customer interaction you had, the more emotional labour was needed.

However, more recently psychologists have expanded their focus to other professions and found burnout can relate more closely to how employees manage their emotions during interactions, rather than the volume of interactions themselves.

Perhaps this morning you turned to a colleague to convey interest in what they said, or had to work hard not to rise to criticism. It may have been that biting your lip rather than expressing feeling hurt was particularly demanding of your inner resource.

But in some cases maintaining the façade can become too much, and the toll is cumulative. Mira W, who preferred not to give her last name, recently left a job with a top airline based in the Middle East because she felt her mental wellbeing was at stake.

In her last position, the “customer was king”, she says. “I once got called 'whore' because a passenger didn't respond when I asked if he wanted coffee. I’d asked him twice and then moved to the next person. I got a tirade of abuse from the man.”

“When I explained what happened to my senior, I was told I must have said or done something to warrant this response… I was then told I should go and apologise.”

“Sometimes I would have to actively choose my facial expression, for example during severe turbulence or an aborted landing,” she says. “Projecting a calm demeanour is essential to keep others calm. So that aspect didn't worry me. It was more the feeling that I had no voice when treated unfairly or extremely rudely.”

During her time with the airline, she encountered abuse and sexism – and was expected to smile through it. “I was constantly having to hide how I felt.