Long johns were first introduced into England in the 17th century, but they did not become popular as sleepwear until the 18th century. They were supposedly called long johns after a famous knife fighter who fought in thermal underwear. They were first used as loungewear but then later became popular as sleepwear. Children also wore them as sleepwear, usually made out of cotton and polyester.
Now that the weather is getting colder it is almost essential to wear them. Long underwear is ideal for sports where muscles need to be kept warm, for skiing, climbing and trekking, and even three-quarter sports pants for winter training and running. In many cases longs johns are equally suitable for men and women.