What causes Insomniacs do have more Nightmares/Dreams than the average person?

I don't know. A lot of times Insomniacs can't sleep becausetheres too much on their mind, so when they do sleep their brain is more active because REM sleep is when you dream the most and when you get the most rest. Just last night i had insomnia and when i finally slept for two hours i had a dream that me and all my friends were on the Black Pearl with Jack Sparrow ^.^