Should I sleep with my bra on?

Question

I have always slept with my bra on. This summer is particularly hot and the sweating makes me feel uncomfortable. I was considering sleeping without a bra.

All the below sentences are quoted directly from different websites*.

1. If poor circulation, skin irritation, restlessness, hyperpigmentation and breast fungus are things you would like to avoid, removing your bra at night is a small and easy precaution you can take.

2. ...it's OK to wear a bra to sleep if you feel like it. Just make sure that it is the right one

3. There is no direct connection between sleeping in a bra and breast cancer, however wearing a bra at night could offer more support or comfort, if needed.

4. I strongly believe that all women SHOULD wear a bra to sleep. The effects of gravity will occur even during the evening when lying down on the bed.

It turns out that there are major arguments for and against sleeping with a bra regardless of the weather.

I would like to know what are the pros and cons of sleeping with and without a bra under the assumption that my bra is a perfect fit and does not by itself cause any problems. I do not want weather to be considered. Should I start sleeping without one for ever or should I always wear one ?
Please note that I am looking for a well reasoned answer with strong medical backing. I am NOT looking for answer which like the links posted here.

<sub>*Sources:
- Should I wear bra on sleep on ShareCare.com
- 5 Reasons You Shouldn’t Wear A Bra While Sleeping on PositiveMEd.com
- Is Sleeping In A Bra Good Or Bad For You? on Huffington Post.</sub>

Answer 1

To answer your question with the best quality evidence would require a double blinded prospective controlled study. Clearly that's not going to happen. But we do have a case control study looking at the bra wearing habits of those with breast cancer, and those without, to see if there is a dose response relationship. And there was none in this group.

We conducted a population-based case–control study of breast cancer in the Seattle–Puget Sound metropolitan area that compared 454 invasive ductal carcinoma (IDC) cases and 590 invasive lobular carcinoma (ILC) cases diagnosed between 2000 and 2004 with 469 control women between 55 to 74 years of age. Information on bra-wearing habits and other breast cancer risk factors was collected from study participants through in-person interviews. Multivariate adjusted odds ratios (OR) and their associated 95% confidence intervals (CI) were estimated using polytomous logistic regression. No aspect of bra wearing, including bra cup size, recency, average number of hours/day worn, wearing a bra with an underwire, or age first began regularly wearing a bra, was associated with risks of either IDC or ILC. Our results did not support an association between bra wearing and increased breast cancer risk among postmenopausal women.

http://m.cebp.aacrjournals.org/content/early/2014/08/27/1055-9965.EPI-14-0414.abstract

Other studies have suggested a link, but this can be explained by the fact that those more likely to wear a bra are more likely to be overweight leading to a larger breast size, and obesity is a well known risk factor for cancer. Larger breasts also imply more breast tissue, and therefore more risk for breast cancer.