Americans will set their clocks back one hour on Nov. 3, 2025, as daylight saving time ends. While the shift may seem minor, disruptions to our sleep schedule can affect how long we spend in rapid eye movement, or REM sleep, the stage most closely tied to dreaming. But how does it all work exactly?
Kimberly Fenn is a professor in the Department of Psychology at Michigan State University’s College of Social Science. Here, she explains what happens to the brain during sleep, why dreams can be so vivid and fleeting, and how time changes can subtly influence our dreaming experience.
What makes dreams so strange and unpredictable?
Dreams are an astonishing state of consciousness. As you sleep, your mind creates fantastic and bizarre stories, rich with visual details — all without any conscious input from you.
The way the brain operates while you’re dreaming explains why dreams can be so fantastic. A small structure called the amygdala is largely responsible for processing emotional information, and it’s very active while dreaming. In contrast, the frontal cortex, which helps you plan and strategize, tends to be rather quiet. This pattern explains why dreams can jump from one peculiar scene to the next, with no clear story line. It’s as if you are sailing an emotional wave, without a captain.
How do scientists study dreams?
To study dreams, researchers ask people to sleep in laboratories with electrodes attached to their scalp. Researchers then monitor a dreamer’s sleep and simply wake them while they’re dreaming and ask them what they were just thinking about. It’s pretty rudimentary science, but it works.
How do scientists know when people are dreaming?
Although dreams can occur in any sleep stage, research has long shown that dreams are most likely to occur during rapid eye movement, or REM, sleep. Scientists can identify REM by the electrical activity on your scalp and your eye movements. They do this by using an electroencephalogram, which uses several small electrodes placed directly on the scalp to measure brain activity. During REM, the dreamer’s eyes move back and forth repeatedly. This likely means they’re scanning — that is, looking around in their dream.
That’s when dream researchers wake up their participants. Dreams are really tricky to study because they evaporate so quickly. So instead of asking participants to remember a dream — even one they were having a moment ago — we ask them what they were just “thinking.” Dreamers don’t have time to think or reflect, they just respond before the dream is lost.
Do most people dream in color or black and white?
As a neuroscientist who studies sleep, I can tell you that approximately 70% of people report dreaming in color, as opposed to just in shades of black and white. But this estimate may be low because scientists can’t actually see what a dreamer sees. There’s no sophisticated technology showing them exactly what’s happening in a dreamer’s mind. Instead, they have to rely on what dreamers remember about their dreams.
Older people report far less color in their dreams than younger people. The prevailing explanation for this is based on the media they experienced while young. If the photographs, movies and television you saw as a child were all in black and white, then you are more likely to report more black-and-white dreams than color dreams.
Are dreams only visual experiences?
Although visual features dominate, you can also hear, smell, taste and feel things in your dreams. So, if you dream about visiting Disneyland, you might hear the music from the parade or smell french fries from a food stand.
Given the visual nature of dreams, you may have wondered whether blind people dream. They do. If a person becomes blind after age 5 or 6, their dreams will contain visual images. However, someone who is congenitally blind, or becomes blind before about age 5, will not have visual images in their dreams. Instead, their dreams contain more information from the other senses.
Why do so many dreams disappear the second we wake up?
The vast majority of dreams are forgotten. That’s because when we’re in REM sleep, the hippocampus, the area of the brain responsible for long-term memory, is largely turned off. The hippocampus is a bit sluggish and takes some time to wake up, so you’re not able to create a long-term memory right after waking.
If you would like to remember your dreams better, simply keep a notepad and pen by your bed and practice writing down your dreams right when you wake. This is the best way to remember the fantastical stories your brain creates for you every night.
Will dreams change due to the shift from daylight saving time?
Your dreams are unlikely to change just because of the time shift. However, REM sleep is highly concentrated in the early mornings. This is why if you use the snooze feature on your alarm, you may find that you can awaken from a dream and then continue the dream until the next time that your alarm chimes. During the autumnal time switch, you will have an extra hour of sleep, so you are more likely to awaken before your alarm. There is a good chance that you will wake from a dream so this might be an excellent time to practice writing down your dream the moment you wake up!
Do our dreams mean anything?
People have been discussing this since ancient times. Sigmund Freud, the founder of psychoanalysis, called dreams the “royal road to the unconscious.” He believed dreams had a profound meaning that’s hidden from the dreamer.
But today, scientists agree that dreams do not have any hidden meaning. So while it’s entertaining to think about what your dreams mean, there’s no scientific basis, for example, to think that a dream about your teeth falling out automatically means you’re anxious about a loss.
Responses and excerpts are from an article published in The Conversation.
