SWEET DREAMS
Dreams: What are they? They are nocturnal sublime learning/decision-testing episodes, whereby the stressful moments (exam, new job, battle, dangers) which occur occasionally in daily life, are stored as visual imagery (information) in the sub-conscious for review and analysis during rest and sleep.
Sleep is the required quiet recharging time, dreams occur every night but most are usually forgotten by morning, since they are typically boring, just like the routines of daily life. Only non-routine events trigger unusually pleasant or unpleasant dreams, which are more likely to be remembered upon waking.
If one loses the ability to dream, one can still learn, but can no longer associate and integrate various thoughts and patterns as well, AFAICT, as this is the primary function of dreams, they are the pattern-weaving story-teller or movie-maker within the self, helping to review in greater detail the various crises that occur, slowing down and analysing moments of indecision of the past day, allowing corrective behavior to become entrained, for the next similar event, therefore providing "virtual experience".
Dina Zaman, author of I Am Muslim, wrote this blog post about a scary dream she had. See the last comment (by Animah) for dream interpretation of it.
http://dina-zaman.blogspot.com/2007/05/my-horrible-horrible-dream.html
[oops, i guess she stopped her blog now]
Do not fear scary dreams, they help you deal with real-life stressful moments without putting you in actual danger, giving you awareness of potential risks and determining the best possible pathways to safety and security. Once that is understood, scary dreams become tools of self-instruction, and are appreciated for their value in survival in a sometimes unpleasant world. Pleasant dreams & fantasies are great escapes, and also have value in life.