Why did couples often sleep in separate beds in the past?

If you've seen shows and movies that are either from or take place in the 1950s, you've probably noticed that married couples sleep in separate, side-by-side beds.

As reported by Curiosity.com twin beds weren't used to show the innocence of relationships back in those days, in fact it was the symbol of a forward-thinking couple.

According to a new book from Hilary Hinds, a literature professor at Lancaster University, this dates back to the 1920s when twin beds had become the modern and fashionable choice for middle-class couples. Twin beds were often simple in design, which came to be seen as a rejection of "old-fashioned" Victorian styles and their heavy, ornate doubles. Single beds were featured as integral elements of the architectural and design visions of Modernists such as Le Corbusier.

This sleeping arrangement also signified a couple's progressive outlook on life, as it balanced their need for togetherness at night with a continuing commitment to separateness and individual autonomy. The identical look of the beds symbolised the egalitarian nature of a married couple — equal sized beds for equally important partners.

Some even considered them the sign of a healthy sexual relationship since spending eight hours in contact every night might reduce a couple's attraction "by making the married pair grow alike physically."

Ideas about couples and marriage changed after World War II, pre war, austerity and housing shortages made sex and procreation less than desirable. But afterward, as incomes rose and couples got married and had children at younger ages.

Possibly as a result, separate beds slowly came to symbolise a troubled marriage, since they literally impeded a couple's physical connection. Twin beds fell out of fashion by the 1960s, bringing to an end what Hinds calls "a bold experiment in 20th-century living".