Nearly 40 percent of us sleep in pyjamas, a little more than 20 percent in our underwear & just under a third wear nothing in bed, according to a survey of 1,200 adults in the UK. Since the average length of time between pyjama washes is 2 weeks (the most common excuse people gave was that their nightwear did not smell), you might think being naked is healthier. After all, your skin needs to breathe, does it not?

The solution

There is not much research on the topic. But first off, skin does not breathe. The idea that air will blow over our naked bodies & we will somehow soak it up just is not true. But sleeping naked does keep you cooler – the optimal temperature for sleeping is around 20C (68F). Insomnia is linked to a large number of conditions like diabetes, obesity, stroke & depression. It’s also corrosive to relationships.

If you’re too hot in bed, then your core temperature will struggle to fall which, according to the Sleep Council, means you will not trigger your “sleep mechanism”. While asleep, your body’s temperature falls naturally after 3 or 4 hours – & wearing fluffy pyjamas under a heavy duvet will disturb that. But, your feet must not get too cold, as that too disturbs sleep. Rather than putting on bed socks, which get hotter by the hour, make use a hot water bottle.

Then there’s the sex & reproductive health angle. Wearing underwear at bedtime adds to the likelihood of your genital region getting sweaty, particularly in summer. For females with conditions like vulvitis, an inflammation of the outer genitalia in which the skin folds are red & swollen with tiny cracks, wearing underwear in a warm bed can promote opportunistic infections like yeast that thrive in dark, sweaty crevices. According to a study in Andrology, males who do not wear pants at night may improve the quality of their sperm. Data from about 500 males in the US showed that those who wore boxers during the day & nothing at night had a 25 percent lower risk of DNA fragmentation in their sperm than those who wore tight pants night & day. Though, the study did not show that their partners were more apt to get pregnant or to do so more rapidly. Research in the Journal of Urology found no major difference between underwear types & semen quality. “It is highly unlikely that underwear has a significant effect on male fertility,” concluded the authors.

In the absence of any proof except that most pyjamas are dirty & you should not overheat, the choice of whether or not to use nightwear is not a health issue. But in the case of those people in surveys who said they wore tracksuits – they really aren’t for sleeping in.