Causes

Exactly what causes premenstrual syndrome is unknown, but several factors may contribute to the condition:

• Cyclic changes in hormones. Signs and symptoms of premenstrual syndrome change with hormonal fluctuations and disappear with pregnancy and menopause.
• Chemical changes in the brain. Fluctuations of serotonin, a brain chemical (neurotransmitter) that's thought to play a crucial role in mood states, could trigger PMS symptoms. Insufficient amounts of serotonin may contribute to premenstrual depression, as well as to fatigue, food cravings and sleep problems.
• Depression. Some women with severe premenstrual syndrome have undiagnosed depression, though depression alone does not cause all of the symptoms