But there’s a less obvious cost of booking with Kiwi.com: sleep deprivation and its negative effect on one’s health. I had only about six hours of sleep during my ordeal and suffered from jet lag for weeks after flying.

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“We know that if you only get light sleep or sleep at the wrong time, your body releases melatonin – a hormone the brain releases at night to drop your body temperature to prepare you for sleep – and this makes things very difficult for you,” says Dr Delwyn Bartlett, an insomnia specialist at the Woolcock Institute of Medical Research in Sydney, Australia.

“Sleep deprivation has cardiovascular consequences [and] memory and performance consequences. And we still don’t know if the consequences are long-term.”

Bartlett says six hours of sleep over 41 hours “is enough to survive” but “not enough to feel good” and that such long periods of travel and transit are best avoided.

That’s easier said than done. Many people cannot afford the sky-high fares now being charged by legacy airlines as a result of volatile oil prices, supply chain issues and surging demand. But I pulled off the return leg of my European tour with a ticket that cost even less than those bought through Kiwi.com.

How? By buying a seat on a budget airline as far in advance as possible.

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A sub-brand of Singapore Airlines, Scoot is the only budget airline connecting Europe and East Asia. It enjoys a perfect safety record and passenger reviews that are a little less stinging than those regularly levelled at other budget airlines.

Skytrax, an airline and airport review site that tallies customer ratings to compare airlines using metrics such as staff service, seat comfort and value for money, gives AirAsia, Jetstar and Cebu Pacific a total score of 4/10 each. Scoot scores 5/10.

I bought a seat on a Scoot flight from Athens, Greece, to Bali with a layover in Singapore a month before departure for US$516. When I revisited Scoot’s website two weeks later, the price of the cheapest seat on the same flight had doubled.

When I checked a third time, a week before my departure, every seat had been sold.

Data from Singapore helps paint a picture of this surging demand. In August 2021, 211,000 passengers travelled through Changi Airport. By August of this year, passenger numbers had shot up to 3.32 million per month.

Data from Singapore Airlines Group shows passenger numbers increased from 600,000 in the 2020-2021 financial year to 3.87 million in 2021-22.

I had flown on a three-hour flight from Perth, Australia, to Bali on Scoot and had no complaints. But the 12-hour marathon between Athens and Singapore would be a different kettle of fish, according to Mike, the owner of an import-export business in Greece who’s travelled to Asia with Scoot on many occasions and who asked for his surname to be withheld.

“You know the secret to surviving this flight?” he says. “Go buy a two-litre water bottle at the supermarket before your flight, empty it and fill it up again at the airport after you pass the security check.

“Otherwise, you have to buy water from them and they charge US$3 for a tiny bottle. You also need to bring a book or a movie on your device because there’s no in-flight entertainment. It gets really boring.”

I also received advice from Bartlett on how to minimise the effects of jet lag before the flight.

“It’s always worse when you fly west to east,” she says, because it’s harder to advance your internal body clock sleep than reverse it. “If you fly east you want to be getting up as early as possible for three or four days before the flight.”

Bartlett shared this hack, too: “As soon as you land, the pilot tells you the local time and most people adjust their watches. But this is unhelpful, as you have no expectations about your sleep.”

The 787 Dreamliner Scoot flies between Athens and Singapore has features the manufacturer Boeing claims minimise the effects of jet lag: dimmable windows, a fuselage that is at a lower pressure than those of other aircraft, and inlets that draw in fresh air from outside to increase the humidity of the air inside.

Hachi Ko, a pilot and air traffic controller in the United States, is one of many aviation professionals who dispute such claims.

“Much has been made of the lower cabin altitude and air-handling system of the 787. But quite honestly, I’ve seen minimal effects from that system among myself and my clients,” Ko writes on Quora, a social question and answer site. “The only thing that can eliminate or reduce jet lag is a time machine.”

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Ko says it all comes down to your specific seat. “I’d still take a refurbished, ergonomic window economy-class seat on an old, crusty 747 versus a middle seat on a 787. I’ll arrive better rested in the window seat on the 747.”

Like most budget airlines, Scoot charges passengers extra to choose its seats. Those who skip this decision risk getting placed in a middle seat. But all the window seats on my flight were already taken.

So I chose a seat in the aisle; it was better than being the piggy in the middle, but I didn’t get any sleep on the first leg of my flight because every time I was about to nod off, I leaned to the side and nearly toppled into the aisle.

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I made up for the lack of sleep during my seven-hour layover in Singapore, where I passed out on a bench for four wonderful hours. That gave me enough energy to survive the next leg of my flight, to Bali, on a Boeing 777 packed with happy tourists, mostly from India.

Flying with Scoot between Europe and Asia isn’t what you’d describe as fun. But it takes 21 hours, about half as long as the flights bought through Kiwi.com – and only four hours more than a flight with a legacy airline that could have cost up to four times as much.

All things considered, the trip I took appears to be the best available option for travelling on a budget between Europe and Asia. But only if you book your ticket well in advance.