It may sound surprising, but experts are cautioning against something many people consider perfectly normal: sleeping in underwear. While it might feel comfortable, studies and health specialists suggest it could be creating long-term problems that go unnoticed until they become difficult to manage.

The team at Belle Lingerie, who compiled extensive research on sleepwear habits, revealed seven unexpected dangers linked to keeping underwear on overnight. And the findings might just convince you to ditch those undies before bed.

Millions of people believe that covering up at night is a matter of comfort, modesty, or even hygiene. But in reality, those habits may be doing more harm than good. The body, particularly sensitive skin and reproductive areas, requires rest and recovery at night—something underwear may actually disrupt.

Here are the surprising reasons why experts recommend giving your body more breathing room while you sleep:

1. Increased Risk of Yeast Infections & UTIs

Few things are more uncomfortable than a urinary tract infection or yeast overgrowth. They can cause itching, burning sensations, and overall misery. Unfortunately, wearing underwear at night creates a warm, humid environment that bacteria and yeast love to thrive in.

Even breathable cotton can trap warmth if it fits snugly against the skin. Over time, this increases the likelihood of infections that require antibiotics or topical treatment. Women, in particular, face greater risk, but men aren’t completely exempt. Experts recommend letting the area “air out” overnight to naturally reduce bacterial growth.

2. Skin Irritation, Rashes, and Fungal Growth

Nighttime is when skin regenerates, but underwear—especially lace, elastic, or synthetic fabrics—can work against this natural process. As you toss and turn, the constant friction combined with sweat can lead to redness, rashes, and even fungal infections.

Those with eczema or sensitive skin are especially vulnerable. Leaving underwear behind, or switching to loose cotton sleepwear, helps the skin heal and stay balanced overnight.

3. Reduced Sperm Count and Male Fertility Issues

For men, temperature regulation is critical. Testicles are naturally designed to stay slightly cooler than body temperature to support sperm production. Wearing tight underwear at night can raise scrotal temperature by several degrees, which has been linked to reduced sperm count and even infertility in medical studies.

One experiment showed that participants exposed to prolonged heat in the groin area experienced long-term fertility issues. Another study found that men who wore insulated jockstraps had measurable drops in sperm count after just three weeks. Underwear at night may unknowingly contribute to similar risks.

4. Poor Air Circulation and Bacterial Build-Up

Healthy skin needs airflow. Without it, sweat and bacteria stay trapped, leading to blocked pores, folliculitis, and even acne-like breakouts in the groin and thigh areas. Experts stress that ventilation is essential for natural skin repair.

Skipping underwear allows the body to regulate temperature better, reduce odor, and minimize irritation.

Even if you don’t notice it, underwear can make you uncomfortable at night. Fabrics can bunch up, dig into the skin, or cause pressure points that subtly wake you up. Over time, these small disruptions affect sleep cycles, resulting in grogginess, poor focus, and irritability during the day.

Choosing looser clothing—or none at all—can lead to deeper, more restorative rest.

Moisture and heat are a recipe for fungal growth, and underwear provides both. Wearing the same pair you’ve had on all day only worsens the problem, as bacteria and sweat accumulate over hours. This makes nighttime the perfect storm for infections like thrush and ringworm.

Modern underwear often contains synthetic fibers treated with chemicals such as dyes and flame retardants. While these additives may seem harmless, prolonged skin contact—especially during 6 to 9 hours of uninterrupted sleep—could gradually affect the endocrine system and disrupt hormone balance.

Researchers are still studying the long-term consequences, but experts agree that minimizing unnecessary exposure is a smart preventive step.

So, What’s the Solution?

The cure is surprisingly simple: take off your underwear before going to sleep. Doing so allows the skin to breathe, reduces the risk of infection, and supports overall reproductive health.

If going fully nude feels uncomfortable, opt for light, breathable cotton pajamas that allow for ventilation without trapping heat and sweat. Your skin—and your sleep—will thank you.