Since the average length of time between pyjama washes is two weeks (the most common excuse people gave was that their nightwear didn't smell), you might think being naked is healthier.

When did you last wash your pyjamas? A mob of Mumsnetters has worked itself into a lather about whether one’s PJs should be washed after every wear. “Oooh, a laundry thread,” as one forum user succinctly put it: “Get ready for neurotics versus mingers …”