Superstition on cutting fingernails at night

The other night I was cutting my fingernails and my mom told me not to cut them at night.  It was weird because my dad has told me the same thing before.  When I had asked my dad why, he didn't give me an answer so I didn't really think much of it.  So when my mom told me not to, I asked her why.  When I heard her response...I nearly started laughing. She said that i'd have nightmares/dreams. haha. I did not believe her and thought it was some stupid chinese superstition.  

Guess what happens the next morning? hahah i woke up with dreams!

CRAZY HUH?