My wife is really light, and her period is over in two days. She usually is horny during her period too but she won't let me "go down" during this time, but we do have sex and it's no big deal to me. Just make sure you use a towel just in case.
My last gf's period was HEAVY and lasted 7 days. This was a no sex time for both of us.
i get extra horny during my period, but i don't like a guys tongue or face down there when i'm "active", but i do like other harder larger things in there, esp. during that time...
I loved having sex with my last g-friend when she was "on!!" Heavy or light, never have to worry about her drying up, plus she liked it better than any other time. Word of caution, use an old red towel to lay her down on, don't want to ruin those nice sheets!!