Why Do We Remember Some Dreams But Not Others?

Why Do We Remember Some Dreams But Not Others?

If you’ve ever woken up on the brink of a heart attack, drenched in sweat and convinced you’ll never live down the shame of sprinting nude through downtown Pittsburgh, you know that some dreams are more memorable than others. Most dreams, in fact, seem totally unmemorable—at least in the sense that we can’t remember them. And yet every now and then a dream will linger into breakfast and well into the day, or month, or year—will become a memory like any other.

Why do some dreams stick with us, while the rest disappear? For this week’s Champions of Illusion: The Science Behind Mind-Boggling Images and Mystifying Brain Puzzles, longlisted for the 2019 AAAS/Subaru Prize for Excellence in Science

One important part of remembering dreams is the fact that you happen to wake up at the time that you’re having a dream.

Everybody dreams every night—but people who tend to remember their dreams more often may be waking up during the REM (rapid eye movement) phase of sleep, which is where dreams with narrative content occur. If you have dreams in the middle of the night but then go on to have other phases of sleep without waking up, then those dreams are mostly going to be inaccessible to you.

Another element is the emotional impact of the dream. To be sure, often times we wake up and we can remember a dream we just had. But dreams, even when we do remember them, tend to vanish pretty quickly; we cannot hold on to most of their details, a good part of the time. If you think back on the dreams that you may have had over the course of your life, probably you can only describe maybe half a dozen. What you’re left with are the most vivid ones, the ones that were especially delightful or especially frightening—that had some emotional impact on you. And that tends to be true for our memories in general—we’re not likely to remember what we eat for breakfast ten years ago, but we definitely are likely to remember almost getting run over by a car.

Stanley Krippner

Professor, Humanistic and Clinical Psychology, Saybrook University

Most dreams are recalled upon awakening in the morning. There are two reasons for this. One is the recency of the dream; the other is that the dreams which come later in the night dreams are often more dramatic and emotional, hence easier to remember.

Of course, dreams can be recalled at any time. Most dreams occur during REM sleep, but some type of mental activity goes on all night long. When this is especially dramatic and emotional, especially in the case of nightmares, a person might awaken suddenly and recall the dream.

However, children often experience a developmental phenomenon called “night terrors.” This does not occur during Rapid Eye Movement (REM) sleep and almost never contains dream content. Parents, of course, do not know the difference between night terrors and nightmares, which children almost always recall.

When people are motivated to remember their dreams and keep a dream notebook or computer file on their dreams, dream recall tends to be more frequent, even before the morning dream period.

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