Angel Is Getting Spayed!!!!!

I have a question. How old does a cat have to be to get spayed?
I read in a book and on the internet that a cat shouldn't be older than one year old to get spayed. I was wondering if that was true.
Angel has been in heat a lot lately (about twice a month-usually lasts from 1 day to two weeks.) She is really annoying my grandma so she wants to get her spayed. Angel is four years old so I was wondering if it was okay to get her spayed.

Thanks everyone! :)

Angel should've been spayed at 6 month of age. Once she's spayed, you won't have to worry about her going through any more heats AND you won't have to worry about her having babies. Assure your granny that once her kitty is fixed, there will be no more sleepless, noisy nights.

Moosmom gave excellent advice!!! Things wil be much better after Angel has been spayed!!!

Thank God! Noiseless nights!
Angel has this boyfriend who is a stray cat. Well, he sits outside the house all night long and meows! He only does this when Angel is in heat. Anyway, Angel goes to the window and meows sooo loud that the cat can hear her with all the windows shut and two stories up! :eek:

Today, me, my grandma and my grandpa decided to get Angel spayed! We took her to the vet. He gave her two shots. I think they were leukemia/FIV and Fecal Exam/Deworming shots. On May 2, the vet is going to give her the booster shots and she is going to get the surgery so she won't have kittens:( Oh well...at least it's less cats homeless and on the street.

Congratulations - it's the right decision on many, many, many levels!