The Great Bra Debate between two of my friends centers on this burning question: Is it healthier to sleep in a bra or to go braless?

To resolve this good-natured feud, I contacted breast expert Jill R. Dietz, MD, of the Cleveland Clinic, who told me that the main purpose of a bra is to prevent ligaments in the breast from stretching, as this can lead to soreness and sagging. The larger your breasts are, the more important it is to have the support of a well-fitting bra during the day when you are sitting, standing and moving. But: Since there is not much pull on the breast ligaments when you are quietly lying down, there is no health-related reason to wear a bra at night.

However, if you feel more comfortable sleeping in a bra, there is no health-related reason not to do so. Despite the dire warnings you may have read on the Internet, wearing a bra to bed will not increase your risk for breast cancer, Dr. Dietz said. It is best, though, to avoid sleeping in a bra that has an underwire or is so tight that it leaves marks on your skin—otherwise, delicate nerves and tissues could be compressed, leading to breast pain, vein blockage or inflammation and/or blocked lymph flow. Instead, Dr. Dietz recommended opting for a style labeled as a “sleep bra,” a type that generally has no wires or tight bands. Also, unlike nylon bras, which can trap moisture and allow an overgrowth of yeast, sleep bras typically are made of a soft, breathable, comfortable material such as cotton.

Bottom line: Both of my friends were right. Whether to wear a bra while you sleep is purely a matter of personal preference.