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. 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. 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. 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. 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. 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. 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. 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. Although they had fewer eye movements during REM sleep than the sighted participants, the blind participants reported the same dream sensations, including visual content. Although the experience can be frightening, it’s perfectly normal and should last only a few minutes before normal muscle control returns. 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.
