Hi M.,
My 8 month old has been fussier at night as well. She is teething and I think that is the cause of her discomfort. Try Hyland's teething tablets - massage them onto the babies gums and they dissolve away. They are wonderful!!
As far as the CIO method, I just want to share my opinion in case it is something you want to try. I am a huge fan of co-sleeping. I would never let my child CIO. It would break my heart, and a crying baby is in need of something - usually connection with mom or dad. So instead, our daughters sleep with us. They are 2.5 years old and 8 months old, and they usually sleep so soundly, I often panic and check them for breathing. We love our family bed and our girls are very secure and rarely cry about anything.
Anyway, co-sleeping is NOT for everyone, but if you want to read more about it, google 'attachment parenting'.
Good luck with whatever you choose,
L.