5 Mind-Bending Facts About Dreams

Most People Have Recurring Dreams

An estimated 60-75% of adults have experienced at least one recurring dream in their lifetime. According to psychology professor Antonio Zadra of the University of Montreal, most recurring dreams are unpleasant, often appearing during periods of real-life stress and dissipating once the stressor is resolved. Many researchers agree that dreaming helps us process emotions and work through unresolved stress, which is why negative recurring dreams may fade once the underlying issue is addressed.

If you’ve ever dreamt about your teeth falling out or being late to a class, you’re not alone. Certain kinds of recurring dreams are common among both adults and children, including falling, being chased, flying, losing teeth, being naked in public, being late, and taking a test. Psychologists speculate that these themes may represent core emotions that emerge at certain points in our lives. For instance, dreams about falling may indicate feelings of anxiety or instability and may arise during times of transition or high stress.

These themes occur across age groups, though the content often differs. Children’s dreams about being chased, for example, often feature the dreamer being pursued by monsters, wild animals, witches, or ghoulish creatures. By contrast, adults may experience being chased by more grown-up concerns such as burglars, strangers, mobs, or shadowy figures.

We Spend an Average of Two Hours Dreaming Each Night

Have you ever had a dream that felt like it lasted an entire day? Chances are it was only minutes long in reality, but those short scenes add up to around two hours of total dreaming per night. 

Most dreams occur during rapid eye movement (REM) sleep, a stage that lasts between 10 minutes and an hour. Because our bodies cycle through sleep stages multiple times per night, we experience an average of four to six REM periods nightly. The first REM period after falling asleep lasts for only a few minutes, so those early dreams are exceptionally brief.

Toward the early hours of the morning, REM periods lengthen, lasting around half an hour, with a maximum length of one hour. Still, it’s rare for a single dream to span that long. Instead, REM periods usually consist of multiple shorter dreams. 

Scientists use several methods to determine the lengths of dreams. One of the most common is electroencephalography (EEG), which measures brainwaves, allowing researchers to determine when participants are in REM sleep and dreaming. Similarly, fMRI (a type of brain imaging) measures blood flow, showing which areas of the brain are active during dreaming. 

Another valuable tool is dream reporting, wherein scientists wake participants after a timed REM period and ask for dream reports, linking REM duration with perceived dream length. Combining those methods helps scientists determine roughly how long the average sleeper dreams. 

Dreams can also occur during the other stages of sleep. There are four sleep stages in total: REM and three phases of non-rapid eye movement (NREM) sleep, N1, N2, and N3. While research indicates NREM dreams do occur, they’re less frequent and much shorter than REM dreams — think of them as a fleeting thought rather than a complex dream featuring storylines and details. That’s because the brain is much more active during REM sleep than during NREM, leading to more vivid dreams.

Because NREM dreams are short, incomplete thoughts rather than full narratives, they don’t account for much of our total dreaming time. This is why researchers use REM duration as a proxy for estimating total dream time, leading to the estimate of roughly two hours of dreaming per night, according to the National Institutes of Health.

Our Brains Temporarily Paralyze Us While We Dream

Have you ever wondered why you don’t fall out of bed during an especially animated dream? The brain has a special protective mechanism to keep us safe and sound: It temporarily paralyzes us during REM, the stage of sleep involving vivid dreaming. When we’re in REM sleep, many physiological changes can occur, including increases in blood pressure, heart rate, brain activity, and breathing. In fact, most neurons in our brains fire just as much, or sometimes more, in deep sleep than they do when we’re awake. 

This allows for very emotional, intense, and elaborate dreams during the REM cycle. Of course, our brains must also protect our bodies from acting out these scenarios. To accomplish this, the pons (the part of the brainstem that handles unconscious processes) and the rostral ventromedial medulla (the part that can block or amplify pain signals sent to the spinal cord) work together to suppress skeletal muscle tone, a process known as muscle atonia. 

That near-total paralysis of voluntary muscles turns physical readiness off during REM sleep, allowing us to sleep soundly. During NREM sleep, muscle tone is reduced but not eliminated, though most NREM dreams are typically less vivid and physically demanding.

Nightmares Are Different From Night Terrors

Bad dreams can take different forms: Nightmares are more common and generally less intense, while night terrors can be severe and disruptive. 

Nightmares are often related to real-life stressors, such as a child’s fear of separation or an adult’s job insecurity. But they may also be fictional and unrelated to waking events. An estimated 20-30% of children and 5-8% of adults experience frequent nightmares, which often occur in the second half of the night, during those longer stretches of REM sleep.

A night terror is far more intense than a nightmare, often startling the dreamer awake. Usually occurring early in the night during NREM sleep, night terrors are caused by the overstimulation of the central nervous system, leading to sudden waking, crying, screaming, confusion, and other unpleasant reactions. Despite those intense responses, night terrors thankfully have a limited recall period, whereas nightmares are more often remembered.

Fortunately, night terrors are relatively uncommon, especially in adults. An estimated 1-6.5% of children (1 to 12 years of age) and 1-4% of adults experience night terrors. They’re most common in toddlers and young kids, but as the nervous system matures, night terrors typically fade without treatment, making them rare in adults.

Some People Can Control Their Dreams

Realizing we’re in a dream — known as lucid dreaming — is a phenomenon that approximately 51% of people have reportedly experienced at least once. Though the ability to control our dreams was once considered a myth, in 1981, a study conducted by psychophysiologist Stephen LaBerge of Stanford University established the scientific validity of lucid dreaming. While in REM sleep and dreaming, study participants were able to perform eye movement patterns that LaBerge had previously asked them to perform, demonstrating that some dreamers can control their actions.

Researchers continue to investigate why we lucid dream. Though many theories are actively being explored, cognitive neurophysiology expert Nicolas Zink, author of the 2015 paper “Theories of Dreaming and Lucid Dreaming,” believes the best explanation is the protoconsciousness theory, which proposes dreaming during REM sleep represents a fundamental state of brain organization that supports waking consciousness and maintains emotional balance.

For many people, the appeal of lucid dreaming lies more in “how” to experience it than “why.” Lucid dreaming can often be pleasant — from traveling the world to soaring through the sky — so some people seek to induce it. One of the most popular techniques is “Mnemonic Induction of Lucid Dreams” (MILD), developed by LaBerge.

The process begins with accurate dream recall upon awakening during the night. According to LaBerge, before falling back asleep, the dreamer must focus on the dream as they repeat, “Next time I’m dreaming, I will remember that I am dreaming.” Repeating this phrase while visualizing the dream may help the dreamer reenter it and become lucid.