What sleeping in a bra is really doing to your boobs.

It’s the big question that causes rifts among friends, divides family members and even generates heated debate between strangers – do you sleep with your bra on or off?

Out of habit, I’m #TeamOff, largely due to a rumour I once heard from a (likely ill-informed) school friend that you need to let your boobs “breathe”. Plus, is there any better feeling than walking in the door and embracing the freedom of removing your bra?

Plenty of my friends are strident #TeamOn supporters though, claiming that they’re doing their bit to battle gravity and keep their boobs ‘perky’. (That made me stop and reconsider, I tell you!)

Add to that headlines claiming there are links between wearing bras to bed and breast cancer or cysts and you have a whole lot of us stressing. Not fun.

So which is actually best and what are the myths that are breast forgotten? We found out.

Myth 1: Sleeping in your bra gives you breast cancer.

Although the subject of a 1995 book entitled Dressed to Kill, you can rest easy knowing this is false.

“Wearing your bra to bed will not cause a girl to develop cancer or stunt her breast growth. It’s also not true that underwire bras cause breast cancer,” said Mary L. Gavin MD, Senior Medical Editor, KidsHealth.

Image: iStock

2. Is it bad for your breast health?

"There is no scientific evidence to confirm that sleeping in your bra is damaging to breasts," says Louisa McKay Managing Director, Costhetics.

However, things can get uncomfortable if your bra is the wrong size.

"Wearing a constrictive bra to sleep affects the physiology of the breast. It can impair the blood flow and lymphatic drainage, which, at worst, can lead to chronic inflammation, oedema (fluid retention) and discomfort," Professor Kefah Mokbel, lead breast surgeon at the London Breast Institute told Bustle.

Listen: How often do you wash your bra? The Mamamia Out Loud team discuss. Post continues after audio. 

3. You really shouldn't sleep in underwire bras.

This one is 100 per cent true.

"I wouldn’t recommend sleeping in a bra that is too tight, or with underwire. If you are wearing a bra with underwires, you may feel uncomfortable during the night," says McKay.

If it rubs too often it can cause rashes or even cysts. (Post continues after gallery.)

4. It keeps them perky.

There are mixed messages on this one, unfortunately.

"There have been a few researchers that have tested the theory that sleeping in a bra prevents sagging. There is no evidence to suggest that this helps at all. Sagging and changes to the breasts are due to many factors such as age and gravity, pregnancy and breastfeeding," says McKay.

However Linda Becker, a professional bra fitter was adamant it does make a difference.

"Either your breasts are being supported for eight hours, or they're not being supported for eight hours. What do you think is better? It's just common sense," she told Huffington Post.

"If your breasts are being held up, they're going to stay up a lot longer. When you take your bra off at the end of the day, they're a lot higher than when you put it on in the morning."

Image: iStock

5. Some people should wear bras.

Of course it's up to personal choice, but there are some people who can benefit from wearing the (right) bra to sleep.

"Some women with larger breasts, or who are breastfeeding, may feel more comfortable at night with the support that a bra can offer," says McKay.

"Also if you have recently had breast augmentation or a reduction it is recommended that you sleep in a lightweight support bra for a few weeks after surgery.

"I would recommend a lightweight cotton or elastane bra, something breathable and definitely without underwire or any padding. Make sure it is well fitting and not too tight."

Ultimately, as long as you steer clear of torturous underwire, it's up to you.