3. It can hep you be in control of your mood
This is especially true for women who are prone to moodiness, thanks to PMS. Most of us expect to be moody a day or two before the blood-flood happens. But PMS actually starts 14 days before the period. So, yes, if you feel like you are in a funk, but your period is still two weeks away, it could still be PMS, and if you track your period, it is easy to confirm that.