Dreams?

Why do we have ugly dreams? Why do dreams feel real? All od my dreams have been about dragons, and how the world ends and fighting agains my self. I did had a scarry one that i had a geart attack in my bday of may 24 2009 i had a chance to see the clock when i callapse to the floor. The time was 10:13 am i was heading to work i saw a chick calling me babe atm moment i dont have a chick she was wearing a sprint shirt and i was to. Mine said on my tag my name and assistante mannager first day lol wierd i was dead for 20 mins.