How much would you pay for an empty row of three or four airline seats?

How much would you pay for exclusive use of a row of three or four economy seats on a long-haul flight? 

Paying for access would enable you to stretch out and sleep for several hours without shelling out for business class.

Airlines are busy testing new ways to travel for when the world opens up again and German airline Lufthansa is testing out ‘sleeper rows’ for its economy passengers.

The airline is currently testing the plan, in which a row of three seats is transformed into a "bed", on its Boeing 747-8 planes between Frankfurt and Sao Paulo in Brazil.

The trial is expected to continue across December and January and, if all goes well, the sleeper rows could be rolled out to each of the airline’s long haul routes.

Passengers pay extra for a row of three or four seats instead of reserving a single seat - and Lufthansa provides a mattress, pillow and a business class blanket to make the beds a little comfier.

Pasengers who book a sleeper row are able to board earlier than other economy passengers so that they can set up their bed.

That's good as it is hard to see any airline crew wanting to step in if another flyer invades a "sleeper" row.

Sleeper rows cost around €220 ($AUD355) on top of the regular fare.

Of course, once we get back to normal, it might be hard to find a seat, let alone a row, to book on a long-haul flight.