It might not be the best marketing to suggest that a car can put its occupants to sleep, but French motor brand Citroen are boasting that they have found the perfect formula for an in-car kip.

Research published this week on what was ‘World Sleep Day’ has found that key components to helping passengers get ‘forty winks’, with comfortable seating and a smooth ride names two of the most important factors.

Falling asleep on a journey is not easily achieved according to Citroen’s research, with 37 per cent of those surveyed admitting that they struggle to sleep as a passenger. The study, which was led by so-called ‘Sleep Geek’, James Wilson, sought the views of 2,000 motorists in the UK, and more than one in three said it is a struggle, 14 per cent said they never sleep on the move.

But for those who do manage to fall asleep 55 per cent said that comfy seating was the most important thing, with a smooth ride (49%) and lots of leg room (26%) also key.

Citroen’s research went so far as to produce a formula for sleeping success.

Optimum In-Car Sleep = C (SP, T, A, L, S) - R

Comfort (C) is a function of Seating Position (SP), Time (T), internal Ambiance (A), Legroom (L) and Suspension (S), while external distractions such as road noise and bumps are characterised by the function (R).

James Wilson, The Sleep Geek, said: “The research provided us with interesting findings, particularly in regards to how difficult some people find it to nap as a passenger in a car, equally something I have come across throughout my work. Ensuring one’s comfort when sleeping is key and working with Citroën to put together a formula that gets people to think about their in-car sleep comfort is something that lots of people will find useful.

"We can often struggle to find time for a powernap, so the car can be an ideal place. Being able to catch a 30-minute power nap during the day, when it’s possible, is really beneficial and can certainly help people to feel reinvigorated.”

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