If you haven't read it, Men, Women and Chainsaws: Gender in the Modern Horror Film Is a great insight into Horror Cinema.

This book is taught in many film schools as its implications extends the bounds of horror.

The concept of the Final Girl was coined in this book.

It also postulates that Women are a focal point of many horror movies because it's more socially acceptable to be afraid for them. Men - at least at the time of writing - were the target demographic, and making the leading role a woman allows them to transcend their gender to embrace a feminine role which allows them to be ok with being scared.

There's a lot more, and the analysis of movies is outstanding.