You'll have hundreds of periods in your life. You'd think that after years of cramps and crankiness, you'd know everything there is to know about that time of the month. But if you're like most women, you still have questions—weird questions—about your period. Discover the truth behind some of the most puzzling mysteries about ever-menstrual ol' Aunt Flo:

Why are my dreams so vivid during PMS?
Although no research concludes that we dream differently in the week before our periods, studies do show that our sleep is disrupted. This is especially true if you have moderate to severe PMS. You may keep waking up during the night, or wake up earlier in the morning, even in the middle of your REM sleep cycle, when you're most likely to be dreaming." Since you remember your dreams only if you wake up from them, waking up often means PMS sufferers may be able to recall their dreams in all their wacky detail.

Why is my blood brownish at the start and end of my period?
When your tampon looks liverish, it means that the blood is trickling from your uterus more slowly. When the flow is more gradual, the blood can oxidize faster and becomes darker. 

What's up with those gross clots? Should I be worried?
Relax. In most cases, they's no cause for alarm. Clots occur when the blood pools somewhere, either in the uterus or vagina, and coagulates. Consult your doctor if you are passing large clots (bigger than a quarter) or experiencing extremely heavy flow (soaking through an overnight pad and tampon within an hour).