Is it bad to sleep in a bra?

While many people can't wait to get home at the end of the day to take off their bras, others prefer to wear the often-uncomfortable undergarment 24/7. Some people might appreciate the extra support while sleeping and even think it's necessary, but there are also rumors that wearing a bra to bed can cause cancer. What's the truth about sleeping in a bra? Is it bad to wear one to bed?

According to the Johns Hopkins All Children's Hospital website, wearing a bra to bed is completely safe. While sleeping in a bra is largely a matter of personal preference, doctors may recommend wearing one if your breasts are sore. The site also debunks rumors that wearing bras to bed — or wearing underwire bras — can cause cancer. Underwire might not be the most comfortable choice to sleep in, but it's not going to give you cancer.

The idea that underwire bras cause cancer seems to stem from a book called  Dressed to Kill by Sydney Ross Singer and Soma Grismaijer. The book, which was published in 1995, claims that bras restrict the lymph system, leading to a buildup of toxins. The authors claimed that women who wore underwire bras for 12 or more hours per day increased their chances of developing breast cancer due to those toxins. It sounds scary, but there's no actual scientific evidence to back up this claim. 

If that still doesn't reassure you, consider a 2014 study published in Cancer Epidemiology, Biomarkers & Prevention (via the National Center for Health Research). The study examined more than 1,000 postmenopausal women with breast cancer, and nearly 500 postmenopausal women without breast cancer. After interviewing the women about their bra wearing habits, the study determined that there is absolutely no evidence that suggests underwire bras pose any sort of increased cancer risk. 

While sleeping in an underwire bra won't give you cancer, it might pose other health problems. "Sleeping in a bra with a wire can give you cysts or irritate your breasts," Dr. Amber Guth told HuffPost.

Wearing a bra that doesn't fit properly can also lead to a host of problems, and wearing it 24 hours a day likely only increases the chances of a negative side effect. "Wearing a bra that is too tight can inhibit flow of lymphatic fluid," Dr. Jamil Abdur-Rahman told Self. "This can cause lymphedema (swelling) of the breasts, which can lead to pain and some temporary skin discoloration." 

That doesn't sound pleasant, and is probably enough to make many people reconsider wearing a bra to bed. Some people, however, find that they need the support that a bra brings. People with large breasts often find that sleeping in a bra is actually more comfortable than going without, since bras keep everything in place. Some people even think that wearing a bra to bed will prevent breasts from sagging (it's said that this is how Marilyn Monroe maintained her physique). Is there any truth to this rumor? 

Again, the answer is no. While sleeping in a well-fitting bra is perfectly safe, it doesn't necessarily provide any benefits beyond additional support if you need it. If you've been sleeping in a bra to keep your breasts perky, you're not doing anything beyond donning an unnecessary layer of clothing. "Sagging is caused by the downwards pull of gravity on the mass of your breasts," Dr. Seth Rankin told Cosmopolitan. "That's why bigger breasts sag more, as there's more fat within the tissue for gravity to work on. When you're lying down flat, the effect of gravity pushes the breast tissue back towards your chest, instead of down towards your toes. So wearing a bra (the purpose of which is ultimately to support breasts from below) is essentially redundant in bed, as breasts naturally compress back down onto the chest."

If you're the type of person who prefers wearing a bra to bed, Parfait Lingerie recommends choosing one without underwire, such as a bralette or a sports bra. It's also a smart idea to have bras specifically for sleeping in, as wearing your day bras to bed will wear them out faster. Again, it's important to make sure that the bra you're sleeping in is comfortable and fits correctly. According to Woman's Day, nearly 80 percent of women are wearing the wrong bra size, so it's a good idea to get measured by a professional at least once a year.