While research into this phenomenon is still ongoing, numerous reasons have already been identified which could contribute to why women suffer from TMD/TMJ more than their male counterparts. First, women are generally more responsive to their emotions and to stress, which in turn makes muscles tense, clenches the jaw, and causes grinding when sleeping. Many women also tend to be magnesium-deficient, and this mineral helps to regulate stress levels. Second, differences in bone structure can also be to blame, as women's jaw bones simply aren't designed the same as a male's jawbone. Jaw bones in men are more robust – longer, wider, and thicker. Third, some researchers believe that estrogen may contribute to TMJ in women, especially since women have estrogen receptors in their jaw. Therefore, if the jaw is misaligned, women may feel the painful symptoms of TMJ more severely than men. Additionally, if a woman has an imbalance of progesterone in her system, this condition could negatively impact bone, collagen, and cartilage, which could in turn cause jaw pain. Lastly, women experience hormone fluctuations more frequently than men, so their experience of pain can drastically change. When estrogen levels are higher, pain may not be felt. At times during the monthly cycle when estrogen is lower, pain may be present or more intense than other times.