[man8alexd]

In the USSR, you usually don't have a spare guest room. An unmarried young man would be lucky to live in a separate apartment; otherwise, it is usually just a bed in a dormitory. At best, it is a one-room (12-20 m2) apartment with a kitchen (10 m2). A hotel is too expensive, so you put your guests into your bed, a folding chair, or a folding cot and go to the kitchen to sleep on a mattress. There were families of 4-5 people who lived in such apartments permanently.

[tjohns]

Even in the US, I don't know many friends with enough living space to have an entire spare guest room. When friends visit, they sleep on the living room couch or an air mattress. Is this not typical?

[dkarl]

Flippant answer: in the U.S., in your twenties, you have no spare space, and visiting friends sleep on your couch. In your forties, you have a guest bedroom, and visiting friends stay at a hotel.

Possibly more accurate answer: it depends on what kind of housing people live in, if they have kids, and if they work at home. Most residential houses were built for couples with children, so if someone owns a house and is single and/or childless, they likely have spare bedrooms that serve as a home offices, hobby spaces, or guest bedrooms. People living in apartments usually don't pay for more space than required for their daily needs.

[cyberax]

Somebody else was likely sleeping in the living room already. The reality of living conditions in the USSR was harsh.

You were typically allocated spacious 9 square meters (96 sq. ft.) of living space per person, with an additional 18 square meters for the head of the family. So a 4-person family would get about 45 square meters (485 sq. ft.)

And these were _typical_ numbers, not a guarantee. Plenty of families had less space.

[hiAndrewQuinn]

I think the operating word here is not "mattress" but "kitchen". How cramped do things have to be to need to put the guest mattress in the kitchen?

[buran77]

In most of the Eastern block the accommodation given to a family was sized for that family. Few had the luxury of a completely unused room.

The kitchen was routinely used as a room for two reasons, one that it was obviously a room, the second because it was easy to heat with the stove being right there. A lot of families were using the kitchen as permanent living space, usually relegating the grandparents to that worst room so the young ones could get a decent start in life.

[Symbiote]

They were 19 and 25.

It doesn't seem that crazy that there would be very little space. Visiting parents and/or grandparents probably got the bedroom, some friends the living room.

[bandrami]

It's less common than it used to be, but in India it's still kind of normal for newlyweds to live in the groom's parents' kitchen for a while until they get their own place