Can I take Vitex for hot flashes?

I am going through menopause and have daily/nightly hot flashes that are driving me crazy! I tried black cohosh but it did not seem to work. I heard that vitex (chaste berry) could relieve hot flashes. Has anyone tried this and had success? How much should I take? I bought the NSI brand which are 400mg per cap and it says to take 2 a day. I thought I should start with just one though.