We can think of a "dream" as a report of a memory of a cognitive experience that happens under the kinds of conditions that are most frequently produced in a state called "sleep." But if you want it to be more simple, you can think of dreams as the little dramas our minds make up when the "self" system is not keeping us alert to the world around us.
Why do we dream? Do dreams have a function or "purpose"?
No one knows for sure. Click here for further discussion.
How often do we dream, and when?
Most people over the age of 10 dream at least 4 to 6 times per night during a stage of sleep called REM (for Rapid Eye Movements, a distinguishing characteristic of this stage of sleep). During REM periods our brains become as active as they are during waking, although not all parts of the brain are reactivated (the parts of the brain that are reactivated in REM are discussed in Chapter 1 of Domhoff's The Scientific Study of Dreams (2003)). REM periods vary in length from 5 to 10 minutes for the first REM period of the night to as long as 30-34 minutes later in the night. It thus seems likely that dreams can be a half hour or more in length.
There is also evidence that we can dream in non-REM sleep in the hour or two before waking up, when the brain has become more activated than it was earlier in the night. That's why we said that we dream "at least" 4 to 6 times per night.
But there are further qualifications that need to be added. Sometimes we can have dreamlike moments during waking if we are in a relaxed state of mind and not noticing anything in our surroundings, as demonstrated in two different studies of people awake in slightly darkened rooms who were signaled at random intervals to say what was going through their minds. And the investigators knew these people were awake because their brain wave activity was being monitored via EEG. So, it may be that we dream any time that the following conditions are met: (1) an adequate level of brain activation; (2) a shutting out of external stimuli; and (3) a shutting down of the self-awareness system that helps focus our minds when we are awake.
One final note: We said that these findings refer to "people over the age of 10." That's because two important studies suggest that children under age 10 only dream in about 20% of their REM periods (again, see Domhoff, 2003).
In summary, we can dream in REM or non-REM sleep, and perhaps even during waking, but we also can have REM sleep without dreaming.
Are dreams influenced by fears or stress? Any other factors?
Most definitely. Dreams often express our current concerns and preoccupations; we call this "the continuity hypothesis." If you are nervous about studying for finals, you may have nervous dreams on the same topic. Dreams are not always about negative preoccupations, though. If you have a crush on someone, it is likely that you will dream about them; if you love basketball, you're more likely to dream about it than someone who doesn't follow the sport.
Why are dreams so forgettable?
It seems likely that all of us forget 95-99% of our dreams for the very ordinary reason that we sleep right through them and aren't paying attention to remembering anything. One dream researcher suggests that it's similar to when you are doing something that doesn't take much concentration, such as driving on an open road, so you are not paying attention to what you are doing.
Are there other mental or personality factors that influence rate of recall?
Some low recallers seem to be less good at tasks involving visual imagination, such as when they have to look at a picture of a building made of blocks and then construct one out of blocks that are sitting in front of them. There may be other "cognitive skills" relating to the ability to imagine things that are important, too, but the research is not yet completely convincing on this point.
As far as personality factors, which many people might think to be the main factor, studies using several personality tests don't show either large or consistent relationships. Nor is there any evidence that some people are too "defensive" or "repressed" to remember their dreams. Several studies are pretty convincing on that point.
Article from: http://psych.ucsc.edu/dreams/FAQ/index.html
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