Sleep and Dreaming Do You Dream Every Night? And Other Fascinating Facts About Dreams By Kendra Cherry Kendra Cherry Facebook Twitter Kendra Cherry, MS, is an author and educational consultant focused on helping students learn about psychology. Learn about our editorial process Updated on October 02, 2022 Medically reviewed Verywell Mind articles are reviewed by board-certified physicians and mental healthcare professionals. Medical Reviewers confirm the content is thorough and accurate, reflecting the latest evidence-based research. Content is reviewed before publication and upon substantial updates. Learn more. by Claudia Chaves, MD Medically reviewed by Claudia Chaves, MD Claudia Chaves, MD, is board-certified in cerebrovascular disease and neurology with a subspecialty certification in vascular neurology. Learn about our Medical Review Board Print Verywell / Brianna Gilmartin We spend roughly one-third of our lives sleeping—and during that time, we dream. Many theories exist to explain why we dream, but researchers still don't know for sure. Some believe dreams have symbolic meaning, whereas others believe that they relate to waking life. What scientists do know is that just about everyone dreams every time they sleep, and those dreams can be fascinating, exciting, terrifying, or just plain weird. Here are 10 things to know about dreams. 9 Common Dreams and What They Mean We Dream Every Night The brain is active all night long. Brain activity in the forebrain and midbrain is particularly intense during rapid eye movement (REM) sleep, which is when we dream. Adults and babies alike dream for around two hours per night, even if they don't remember it. In fact, researchers have found that people usually have several dreams each night, each typically lasting for five to 20 minutes. During a typical lifetime, people spend an average of six years dreaming. 5 Major Characteristics of Dreams We Forget Most of Our Dreams 1:49 7 Theories on Why We Dream Simplified We forget up to 95% of all dreams shortly after waking. According to one theory about why dreams are so difficult to remember, changes in the brain during sleep don't support the information processing and storage needed to form memories. Brain scans of sleepers have shown that the frontal lobes—the area that plays a key role in memory formation—are inactive during REM sleep, the stage in which dreaming occurs. We might also forget our dreams because of changes in the levels of certain neurotransmitters, specifically acetylcholine and norepinephrine, during REM sleep. Yet another study found a link between dream recall and the brain matter density of the medial prefrontal cortex (MPFC). Participants with higher white matter density reported higher dream recall. Not All Dreams Are in Color Most people report dreaming in color, but roughly 12% of people claim to dream only in black and white. In studies in which dreamers have been awakened and asked to select colors that match those in their dreams, people chose soft pastel colors most frequently. People younger than 25 rarely report dreaming in black and white. However, people older than 55 report black and white dreams about 25% of the time. Researchers believe this difference results from childhood exposure to black-and-white television. This idea is supported by an older study, which found that people in the 1940s rarely reported dreaming in color. Men and Women Dream Differently Researchers have found differences between men and women in dream content. In several studies, men reported dreaming about weapons significantly more often than women did, whereas women dreamed about clothing more often than men. Another study showed that men's dreams tend to have more aggressive content and physical activity, whereas women's dreams contain more rejection and exclusion, as well as more conversation than physical activity. Women tend to have slightly longer dreams with more characters. Men dream about other men twice as often as they do about women; women tend to dream about both sexes equally. Animals Probably Dream Many think that, when a sleeping dog wags its tail or a sleeping cat swats its paws, it's dreaming. Although no one can say for sure, researchers believe that most animals go through REM and non-REM sleep stages, so they probably do dream. Animals might not experience dreams in the same way as humans, however. In other words, they might not remember images or attach a storyline to them. You Can Control Your Dreams A lucid dream is one in which you're aware that you're dreaming even though you're still asleep. Lucid dreaming is thought to be a combination of consciousness and REM sleep, during which you can direct or control the dream content. People can learn how to have lucid dreams using various techniques, including mnemonic induction of lucid dreams (MILD) and senses-initiated lucid dreams (SSILD). These involve waking up after five hours and repeating a phrase like "I will remember my dream," or focusing on the stimuli (sights, sounds, sensations) in your sleep environment, respectively. Approximately half of all people can remember at least one instance of lucid dreaming, and some are able to have lucid dreams frequently. Negative Dreams Are More Common Researcher Calvin S. Hall, Ph.D., collected more than 50,000 dream accounts from college students over more than 40 years. Made available to the public in the 1990s by Hall's student, William Domhoff, the dream accounts reported many emotions during dreams. Several factors affect the emotional content of dreams, including anxiety, stress, and certain medications. One study found that external stimuli, including good and bad smells, can play a role in positive and negative dreams. The most common emotion experienced in dreams is anxiety. Generally, negative emotions are much more common than positive ones. Dream Interpretation: What Do Dreams Mean? Blind People May Dream Visually In one study of people who have been blind since birth, they still seemed to experience visual imagery in their dreams, and they had eye movements that correlated to visual dream recall. Although they had fewer eye movements during REM sleep than the sighted participants, the blind participants reported the same dream sensations, including visual content. You're Paralyzed While Dreaming REM sleep is characterized by paralysis of the voluntary muscles. This phenomenon is known as REM atonia and prevents you from acting out your dreams while you're asleep. Basically, because motor neurons are not stimulated, your body does not move. In some cases, this paralysis can even carry over into the waking state for as long as 10 minutes, a condition known as sleep paralysis. Although the experience can be frightening, it's perfectly normal and should last only a few minutes before normal muscle control returns. Some Dreams Are Universal Although dreams are often influenced by personal experience, researchers have found that certain dream themes are common across cultures. For example, people from all over the world frequently dream about being chased, being attacked, or falling. Other common dream experiences include feeling frozen and unable to move, arriving late, flying, and being naked in public. 18 Sources Verywell Mind uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. 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