I was wondering how do you know when you're meditating that a spirit guide is speaking with you and do they do it in dreams because I've been having dreams that make no sense to me... I guess I'm a little confused on how to go about communicating with them.

Practicing meditation we use things like visualization to create our own experiences.  Contact with your own spirit guide is one exercise to practice.

Visualize a scene from nature (garden, waterfall, tree, etc) on which to meditate.  When the body is quieted and the spirit open, pick a symbol (from your scene) and place it foremost in your mind's eye along with a seat and just invite your guide to join you.

I don't know about anyone else but I am claircognizant and I just know things. I usually meditate right before bed and I know my guides come to me in my sleep state. in the beginning I could not retain any of the information but as time went on and I had done some work on myself and began to discern my thoughts from the guidance, I realize that I am able to retain the information. I not only retain the information I have awareness in my dream state now. Some nights I feel like I am up all night working with spirit. I work with my guides, angels, archangel, ascended masters and god. They give me a lot of insight. I have a wonderful team. For me the biggest thing was trust. I had to trust that the process was happening and not doubt the experience. I also had to surrender my control of the outcomes. If you let be then you will be.

You dreams are all about your unresolved emotions from your conscious state.  They are not psychic or about spirit contact at all.  And nor should spirit guides interfere in your health by interupting much needed rest.  The spirit guides would just not do so.

All contact and exercises for that purpose are done in meditation.  You can use all the tools of your own consciousness, visualization, meditation, affirmation to understand and connect with spirit guides.  It is really all about energy and the changes you feel within when attuned to a spirit guide.

When you need some help and direction let me know - I would be more than willing to help.  Finding a good teacher in your own environment is really the best to do to get understanding about spirit guides and the work of mediumship and psychic abilities.