I usually get turned on only while on my period, why could this be?

C • TTC for 6 1/2 years
I normally don't get turned on just thinking about sex or knowing I'm about to have sex. I do have orgasms during intercourse but I mean just the thought of it. But when I'm on my period(like today) just the thought of sex or imagining sexual acts makes me so tingly down there, literally it will take less than a minute for me to come if I masturbated. In a way it sucks because I can't have intercourse or masturbate. This is totally the opposite of what should happen. do any of you experience this?