(CNN) -- You're in a classroom and the teacher puts an exam face down on your desk. You pick it up and can't really make out what's on it; it's blurry, or it's in another language, or it's in a subject you didn't study.
You feel like you're going to fail, even though it's been years since you've actually been in school.
People commonly relive this scenario in their dreams, even decades after their last graduation. While many high school, college and graduate school students are cramming for real exams this week, you may dream about it if you have anxiety about being judged, or if you're in a situation you don't know how to handle, experts say.
Dreams are "an extremely rich source of practical advice, and other alternatives about what we're doing in our lives," said Deirdre Barrett, Harvard psychologist and author of "The Committee of Sleep" and "Trauma and Dreams." "They're just coming from such a different part of ourselves that they're a very good supplement to our waking, rational thinking."
The dreaming brain
Scientists know about as much about the dreaming brain as they do the waking brain -- in other words, there's still a lot to learn about how the brain creates the dreaming consciousness and wakeful consciousness, said William Dement, leading sleep researcher at Stanford University.
Dreaming happens during the REM (rapid eye movement) stage of sleep. In a typical sleep cycle, there are 68 minutes of non-REM sleep and 22 minutes of REM sleep. An eight-hour night of sleep will include about six REM periods, during which multiple dreams can occur.
The body is temporarily paralyzed during REM sleep. But in a rare condition called REM behavior disorder, people act out what they are doing in their dreams, be it talking or running into a wall.
You are conscious in your dreams in basically the same way you are conscious in real life, but you don't remember dreams as well because memory processing is down, Dement said. The continuity of real life experiences helps you distinguish waking life from the dream world. For example, you don't magically reappear in a different setting in the real world, whereas it might appear that way in a single night of dreaming.
"In some ways, it's very good we don't remember our dreams very well," he said. "You'd constantly be saying, 'Did that happen, or was it a dream?' "
Inside your dreams
The symbols and events in dreams can mean many different things to different people, Barrett said. A dog might signal unconditional love to someone who has positive feelings toward canines; someone else with a fear of dogs might dream about them as a reflection of trauma.
But themes such as the "test you're not prepared for" do tend to have common meanings for people. A similar dream occurs for people who had experience in acting as a child: They dream that they forgot there was an audition that day, or that they get to an audition and it's in a garbled language, or they studied the wrong script -- they're being judged, or don't know what to do in this situation. People also commonly have dreams in which they are naked in public, associated with feeling exposed or ashamed. This could signal that the dreamer feels socially inadequate in some way, Barrett said
These are "psychological dreams" that are telling you that you should figure out where in life you are having a block, or how you should handle your difficult problem, said Dr. Judith Orloff, author of "Second Sight" and assistant clinical professor of psychiatry at the University of California, Los Angeles.
Nightmares can shed light into the dark areas of people's lives, Orloff said. They confront people with what they are most afraid of, and can be used to work through underlying problems.
Orloff had one patient who repeatedly dreamed she was being chased on a cliff by an "evil pursuer" who was going to hurt her. The patient and psychologist figured out that the pursuer represented the woman's abusive father. After working through it, the nightmare did not repeat.
Letting your dreams help you
If you want further insight into a difficult decision, consider asking a question before you go to bed, and then seeing what happens in your dream, Orloff said. Get a dream journal and write down the question at night; in the morning, without getting out of bed, write down everything you remember.
One patient of Orloff's had to make a difficult decision about whether to take a new job, and dreamed that she was in the new position but had a negative experience. This helped her realize that she did not get along with the boss, and she decided against the job, Orloff said.
Dement said he is somewhat skeptical about putting a lot of weight in dream interpretation. Dreams are often hard to remember, the associations in them can mean multiple things, and you shouldn't stress if you can't recall details, he said. It can be quite difficult to summon a memorable dream to answer a question in the way that Orloff recommends, he said.
But Dement agreed that dreams can help with major life events. He himself once had a life-changing dream: He had been trying to quit smoking, but simply could not, and dreamed that he had coughed up pink sputum indicative of cancer.
"I felt just utter complete despair -- I would never see my children grow up, I did it to myself because I didn't quit, I hadn't put enough aside to take care of my family," he said. "Then I woke up. I never smoked another cigarette."
Important discoveries have also emerged as a consequence of dreams. Otto Loewi, a German pharmacologist, is said to have dreamed about an experiment to show that the transmission of nerve impulses is chemical, not electrical. The experiment worked in real life, and Loewi went on to the Nobel Prize in medicine in 1936.
Some artists and musicians use their dreams for inspiration. The writer Robert Louis Stevenson drew on his dreams for "The Strange Case of Dr. Jekyll and Mr. Hyde."
The bottom line: Trust your waking, logical thinking, but don't ignore what your intuitive, feeling-based, visual side might have to say about difficult decisions through dreams, Barrett said.
"It can be very important to look to our dreams on anything that we're kind of stuck on in our waking lives, because the dream thoughts are likely to be so different, and they may really think outside the box and come up with an answer that we haven't awake," Barrett said.