"I think it does catch some women off guard, that they've started experiencing some of these things particularly like mood swings and difficulty sleeping," says Dr. Martha Brewer, OB/GYN at UAMS.
What's so surprising-- for many women, Dr. Brewer says, is you can still have a menstrual cycle.
"You're starting to think, gosh something's wrong, and people usually run in and have a complete check up by somebody and don't have any more information and are still having the same symptoms," Dr. Brewer says.
Those symptoms include erratic periods, mood swings or irritability, night hot flashes, and in some cases, fewer cramps during your period.
Doctors say this state of "in-between" can last as long as ten years... even affecting a woman's relationship with her husband and family.
"Most women with families basically have been sacrificing themselves for the benefit of the family for the most part of their life and once the kids are up and out of the nest, or at least in high school, they might start reevaluating their priorities."