The seven unknown health dangers of sleeping in your underwear

Britons tucking themselves into bed could be sleep-walking into a health crisis over their choice and fitting of night attire, experts claim. Sleepwear makers warn that our washing habits, choice of sleepwear materials, how tight our nightwear fits and how often we launder our PJs can all affect our bodies.

Now the team at Belle Lingerie have warned of seven health nightwear dangers and given tips on how to boost your health as you sleep - and not damage it. They even suggest that sleeping naked, or 'commando', could even be a healthier choice.

A spokesperson at Belle Lingerie explained: "Sleeping without underwear comes with many hidden health benefits.

"It lets the skin breathe, which reduces the risk of infections and can even support male fertility. If going fully nude feels strange, you can try wearing loose-fitting pyjamas made from natural fabrics like bamboo or cotton.

"Studies have also shown that sleeping naked helps control the body’s core temperature, promoting deeper sleep, whilst reducing stress, boosting circulation, and improving intimacy."

Listing and explaining the seven health nightwear dangers one by one, they recommend how to avoid them.

Increased Risk of Yeast Infections & UTIs:

Underwear creates a warm space, which is the perfect breeding ground for yeast and bacteria. For women, this may cause an increased risk of thrush or urinary tract infection, which at least 75% of women will experience once in their lifetime.

Even cotton, which is known for being more breathable than other synthetic fabrics, isn’t enough to completely rule out these conditions if worn tightly against the skin all night. It’s recommended to allow this area to ‘air out’ overnight, giving the body a break from clingy clothing and lowering the chances of recurrent infections.

Skin Irritation & Rashes:

Night-time is a time when your skin rests and repairs; however, underwear can disrupt this process. Lace edges, elastic waistbands, or synthetic fabrics rub against the skin for hours, especially if you fidget in your sleep.

When this is mixed with the natural sweat your body makes overnight, the friction can lead to redness, rashes, and even fungal flare-ups. If you suffer from skin conditions such as eczema, you may find that your symptoms worsen when sleeping in underwear.

Reduced Sperm Health in Men:

Research has shown that even a slight rise in scrotal temperature can have a huge impact on sperm production. One study even found that men who wore loose-fitting underwear had remarkably higher sperm counts and concentrations than those who wore tighter pants.

Restrictive underwear, especially when slept in, keeps the testicles warmer than they should be, which can interfere with sperm quality and, over time, impact fertility. For men, sleeping without underwear supports healthier reproductive function by regulating the temperature.

Poor Air Circulation:

Our skin regenerates at night, but it can only successfully do so with proper ventilation. Underwear reduces airflow to these areas, keeping bacteria and sweat close to the skin.

Poor circulation can lead to folliculitis (inflamed hair follicles), blocked pores, and unpleasant odours. Sometimes it can also cause acne-like breakouts in the thigh and groin area. By removing underwear, the skin can breathe and repair itself more productively.

Disrupted Sleep Quality:

Sleep quality is heavily influenced by comfort, and underwear can get in the way of this in many ways. Material that twists or bunches, elastic that digs into the skin, and tight seams during the night all can cause irritation levels; however, this can build up higher.

Even if you don’t fully wake, your body goes through minor disturbances that get you out of deep sleep. If this continues, it can leave you feeling tired, less focused, and groggy the next day, all because your underwear is quietly ruining your rest.

Increased Risk of Fungal Infections:

Fungal infections grow in dark, damp, and warm surroundings, the exact conditions that underwear create when worn to bed. The fungus responsible for thrush can adapt overnight in these conditions.

Men are not immune to it; it’s common for fungal infections to grow in the groin area. Going to bed in the dame underwear you wore all day creates an even higher risk as bacteria and fungi from the day is transferred onto the skin for hours at a time. Not sleeping in underwear will lower these risks.

Hormone Disruption from Synthetic Fabrics:

It’s common that most underwear is made from synthetic fabrics that are treated with flame-retardant chemicals, dyes, and finishes. These materials can get into the skin during a long time of contact, and especially in sensitive areas where the skin barriers may be thin.

Some research suggests that these chemicals may play havoc with the endocrine system, disrupting hormone balance. The long-tern risks are still being studied; it’s recommended to avoid unnecessary exposure where possible, like during the six to nine hours of sleep.

Five Tips for a Healthier Sleep Routine:

Shower before bed – Wash away any sweat and bacteria that has accumulated during the day to reduce the risk of infection under the covers.

Choose breathable fabrics – Wear loose-fitting, 100% cotton fabrics that allow the skin to breathe, if wearing underwear suits you better.

Go commando when possible – Even if it's just a few nights a week, give your body a break from underwear.

Rotate your sleepwear – Change into clean pyjamas and underwear daily as re-wearing them increases bacteria build-up.

Keep bedding fresh – Wash sheets at least once a week, to get rid of remaining bacteria, skin cells, and sweat.