Researchers believe that dreaming is a means for us to regulate our moods and consolidate our memories. The more we sleep, the more dream time we have. Most people dream between four to six times each night, yet forget around 95 to 99 percent. Some scientists theorize this is due to a hormone that helps us remember and make sense of things shutting off while we sleep.Even while sleeping, however, the brain remains active. Whatever experiences we encounter during the day, as well as the last thoughts that scurry through our brains right before falling asleep, influence dream content. They determine not only what we dream, but the type of dreams we experience.

Most dreaming begins during REM sleep

Although people dream throughout the night, we are most likely to remember those that occur during rapid eye movement (REM) sleep, which starts about 90 minutes after we doze off. During this phase, the eyes move quickly in different directions, and respirations and brain activity increase. The brain restrains voluntary muscles like those in the arms and legs to prevent self-harm. That’s why we sometimes feel trapped or unable to escape during dreams. A period of REM sleep can last for up to an hour. But before we fall into REM, we cycle through four other stages, repeat the third, then progress through the second stage. After REM, we go back to the second stage. This cycle repeats up to five times each night.

Standard dreams can be both good and bad

Themes vary for standard dreams. Most of the time, they depict stories that mirror everyday life and include people and locations we’re familiar with. Others reveal bizarre or fantastical events. Dreams can be beautiful and reassuring, but they can also put a spotlight on a situation we’re feeling unsure about or focus on a difficult decision we have to make. Bad dreams, unlike nightmares, rarely cause a person to wake up so that they can end the dream. They usually revolve around themes of aggression, helplessness, or interpersonal conflicts, but even more themes can surface during a nightmare.

Nightmares are bad dreams that wake you up

Nightmares often contain the same themes as bad dreams, such as fear. Nightmares, however, are more intense, with physical aggression occurring more frequently. Studies show that evil presences and being chased are the most common themes. Some research suggests that women have more nightmares than men, usually involving interpersonal relationships. Men’s nightmares generally focus on physical altercations, major calamities, or disasters. Interestingly, nightmares contain fewer failed outcomes than our usual, everyday dreams.

Lucid dreams are controllable dreams

Sometimes, you know you’re dreaming. In lucid dreaming, the dreamer controls the events they experience. Some people say they can direct themselves to perform certain acts, such as fighting or escaping a situation. Others say they can act out sexual fantasies. Around 55% of people report having lucid dreams. Research indicates that lucid dreaming triggers certain activations in the brain that can be beneficial for easing stress and boosting creativity. Other studies say that lucid dreams can provide relief from recurring nightmares.

Recurring dreams often happen during stressful times

Sleep experts describe recurring dreams as those that repeat or occur frequently and usually contain negative content. Most of these dreams have specific themes, such as falling, losing control of a car, failing an exam, being late, or getting stuck. Studies show that these types of dreams can indicate poor psychological health. They may also reveal stressors or unresolved conflicts in a person’s life. Resolving the conflict in the dream may improve conscious well-being. As with nightmares, women are more likely than men to experience recurring dreams.

Prophetic dreams have roots in subconscious clues

Throughout time, cultures have attributed predictive powers to divine intervention or some type of spiritual connection. While prophetic dreams seem improbable, there have been scientific studies focusing on this phenomenon. Most conclude that the dreamers are not prophesizing, but putting together concrete clues that they received during their waking hours, while in the REM state. Famously, President Abraham Lincoln predicted his death in a dream. However, he had been the target of numerous death threats, especially after the Civil War. It is likely his dream reflected these clues because of his worry over an assassination attempt.

Healing dreams soothe stress, anxiety, and trauma

Researchers have known for a long time that sleep helps the brain rebound after a tough day. Additionally, people who’ve experienced trauma often process it through dreams. Our brains consolidate memories and boost other essential functions while we’re asleep. Plus, there’s a significant decrease in norepinephrine, a natural stress chemical, during REM sleep. When this chemical is low, the brain processes emotional experiences in a safer environment — our non-lucid dreams.

Vivid dreams are intricate and sometimes disturbing

As the REM sleep stage increases, dreams can become more vivid. Sometimes these dreams can be so lifelike that it’s hard to distinguish them from reality, and upon waking, the dreamer can usually recall them in detail. Sleep deprivation, hormone fluctuations, traumatic events, and stress can lead to vivid dreams. Alcohol and some drugs inhibit REM sleep and dreams, which can lead to vivid dreams the following nights. People with narcolepsy may experience these dreams because they enter REM sleep quickly. Some pregnant women also report having vivid dreams that stop after the birth of their child.

Daydreams are also therapeutic

During a daydream, we’re neither asleep nor awake. Unlike dreams, daydreams lack any symbolism. But like the dreams that occur when we sleep, they can be therapeutic. Most adults believe that daydreaming is a poor use of time, but experts disagree, arguing these moments of distraction relieve stress, frustration, and boredom, and are also entertaining. They’re a private way for us to prepare for what life has in store and to review past experiences. Recurring daydreams may be a signal that you need to change something in your life, say psychologists.

False awakenings are a dream within a dream

Dreaming that you’re awake when you’re still sleeping is called a false awakening. These “double dreams” sometimes occur when someone adheres closely to a regular waking routine. While still asleep, they dream that they’re following their normal schedule. Sometimes, an unusual occurrence in their dreamed routine causes them to panic and wake up. Other individuals dream that they have woken up, yet they are still asleep. Dream experts say that anxiety and stress lead to false awakenings.