Written by Rebecca Levi

Reviewed by Dr. Michael Breus

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Everyone dreams, but we don’t always remember our dreams the next day. Perhaps because of their elusiveness, dreams have interested people throughout history. In ancient cultures, dreams were thought to contain messages from the gods. In the early 20th century, some proposed the idea that dreams held symbolic messages from the subconscious.

Even now, experts still don’t know exactly why we dream.

Dreams continue to be an area of investigation and interest. Dream interpretation is sometimes used during psychotherapy, and many books claim to identify the hidden meanings behind common dreams. In the scientific sphere, researchers are exploring how lucid dreaming can affect post-traumatic stress disorder (PTSD) and whether dreams have any meaning at all.

There is still much to learn about dreams and dreaming. For now, we’ll take a look at some popular theories about why we dream, different types of dreams, and how our waking thoughts affect our dreams.

Key Takeaways


  • Dreams can consist of a mix of thoughts, images, and sensations and commonly occur during the REM phase of sleep.
  • The purpose of dreams is still debated, with theories suggesting emotional processing, conflict solving, and cognitive enhancement.
  • Dream symbols and themes may provide personal insight into the dreamer’s thoughts and emotions.
  • Try to recall and interpret your dreams by keeping a dream journal.

Why Do We Dream?

No one knows for sure why we dream, although there are many theories.

  • Emotional processing: Dreaming may help the brain process emotions. It’s common to dream about significant events from waking life. Strong, negative emotional states like anxiety and stress are also known to trigger bad dreams. This may be why up to 80% of people with PTSD experience frequent nightmares.
  • The continuity hypothesis: The continuity hypothesis states that most dreams reflect the same concepts and concerns as our waking thoughts. As a result, we may be able to identify our biggest worries by examining the content of our recurring dreams or dream images. 
  • Memory consolidation: Some researchers believe dreams play a part in memory formation. Evidence suggests that the sleeping brain sorts, processes, and stores information from waking life, turning important information into memories. Dreams may also reflect the images and concepts that are stored as long-term memories.
  • Generalization: According to the relatively new overfitted brain hypothesis, the brain gets used to the same inputs and experiences people get in everyday life. Over time, we’re less able to respond to new experiences. This theory suggests that the strangeness of dreams disrupts this cycle, helping us to stay sharp.
  • Creative problem solving: Some experts have proposed that dreaming aids in problem solving during waking life. This theory suggests that dreams give us a chance to “rehearse” scenarios or create and try out new options. 
  • No purpose: A few researchers think that dreams do not serve any particular purpose. They believe that dreams simply contain discarded information that is not significant in any way. They assert that humans invented purposes for dreams after the fact, using them to predict the future or tell stories.

What Are Dreams?

Dreams are images and experiences people have while they sleep. The contents of dreams, researchers believe, are unique to the individual. They combine fragments of a person’s experiences, worries, and waking thoughts into new scenarios.

Many people dream in color, but some dream only in black and white. Although most people “see” dream imagery, some also experience physical sensations or hear sounds in their dreams. Dreams often contain strange images and scenarios that may change rapidly. 

Time and perspective in dreams can be different from waking life. For example, a person may experience a dream as a participant and a spectator at the same time.

Nightmares are dreams that are frightening and often vivid. They tend to feature upsetting themes like being in physical danger. They are common in childhood and among people with PTSD, although some individuals experience frequent nightmares throughout their lives.

When Does Dreaming Occur?

Most people spend around two hours dreaming every night. Dreams may occur in any stage of sleep, but most dreaming takes place during rapid eye movement (REM) sleep. Dreams that happen during REM sleep are more vivid than dreams that occur during other stages. Most nightmares also take place during periods of REM sleep.

There are two types of sleep: REM, which is just one stage, and non-REM, which consists of three stages. Each stage involves different brain and body mechanisms. People usually cycle through all four stages multiple times in one night. The longest and deepest periods of REM sleep tend to happen closer to morning.

During REM sleep, your arm and leg muscles become paralyzed. This keeps you from getting up and acting out your dreams.

Do Dreams Affect Our Sleep?

Dreams can impact the quality and quantity of the sleep we get. People who have frequent nightmares can develop anxiety about sleep and dreaming. If nightmares wake them up or cause fitful sleeping, they may also experience cognitive symptoms of sleep deprivation, such as impaired memory and inability to concentrate.

However, the kind of sleep we get can also affect our dreams. High quality, restful sleep may prevent nightmares, for example.

Common Types of Dreams

There are many different types of dreams. Common images or themes that many people experience include flying, being chased, failing a test, or falling. Some, such as fever dreams, may only occur during a particular physical or mental state.

  • Recurring dreams: These dreams happen night after night or several nights over time and feature similar situations and events. Some researchers think recurring dreams are the result of unsatisfied psychological needs. They believe that these dreams occur when a person experiences a long-term, unresolved conflict.
  • Vivid dreams: Vivid dreams may be easier to recall due to their strong imagery. They may also feel more “real” than other dreams.
  • Nightmares: Nightmares are vivid, disturbing dreams that often cause anxiety. They are more common during stressful periods and after traumatic experiences. People who have nightmare disorder experience recurring bad dreams, sometimes having multiple nightmares in one night.
  • Lucid dreams: Lucid dreaming occurs when a person is aware that they are dreaming but does not wake up. The individual is able to control their actions and events within the dream. People may be able to induce lucid dreams through brain training or taking medications.
  • Fever dreams: Fevers can trigger strange and unpleasant dreams. Common themes of fever dreams include distorted spaces, physical threats, illness or health-related concerns, and heat.

How to Interpret Your Dreams

Many books and websites offer dream interpretation guides that claim to reveal the meanings behind common dream imagery. It’s worth noting there is no evidence that dreams contain any more symbolism than our waking thoughts.

Instead, some researchers believe dreams are made up of bits and pieces of images, concerns, and scenarios from our day-to-day lives. This means that most dreams are unique and are only meaningful to the individual.

Our physical and mental health can also impact the contents of our dreams. Fever dreams, for example, are often about being sick or being too hot. People with certain health conditions are more likely to experience nightmares. These include:

  • PTSD
  • Acute stress disorder
  • Narcolepsy
  • Anxiety disorder
  • Depression
  • Schizophrenia
  • Borderline personality disorder

While a variety of influences may affect our dreams, some people believe that certain common dreams have a particular meaning.

  • Teeth falling out: Dreams about losing teeth are almost universal. Some have suggested losing teeth in a dream symbolizes psychological distress, but a recent study asserts they may simply be related to jaw or tooth pain.
  • Being chased: Like many common nightmare scenarios, dreams about being chased may indicate that you are stressed. Nightmares occur more often during stressful periods or after negative experiences.
  • Having an affair: You may be more likely to dream that you or your partner is having an affair if you have been cheated on in the past. These dreams can also be a sign that you are jealous in romantic relationships or that you lack intimacy in waking life.

Tips to Help You Recall Dreams

Researchers think that the best way to remember your dreams is to tell yourself that your dreams are meaningful or important. There are a few ways you may be able to reinforce the idea that your dreams matter.

  • Write them down: Keep a notebook and pen beside your bed so you can write down your dreams as soon as you wake up. If you find it inconvenient or difficult to put your dreams on paper, consider using a voice recorder, or try a dream journal app.
  • Try vitamin B6: Some evidence suggests that taking vitamin B6 before bed may help you remember your dreams. Researchers theorize that the vitamin might be useful for lucid dreaming.
  • Remind yourself: Before you fall asleep, tell yourself that you will remember your dreams when you wake up.

How to Lucid Dream

Lucid dreaming may have several uses. Neuroscientists are interested in lucid dreaming because it could potentially help them explore consciousness. Some therapists are exploring lucid dreaming as a way to help people with PTSD cope with depression and anxiety due to nightmares. Finally, many people explore lucid dreaming out of personal interest.

There are numerous techniques and tricks that are meant to induce lucid dreaming.

  • State your intention: The next time you are lying down, remember your most recent dream. Envision yourself back in that dream. Tell yourself with strong intention that the next time you are dreaming, you will remember that you are dreaming. 
  • Practice reality testing: Certain actions might make it easier to realize you’re dreaming. These include trying to exhale through your closed mouth and attempting to push the fingers of one hand through the other.
  • Condition your mind and body: Some people believe that there is an optimal physical state for inducing lucid dreaming. They focus on their surroundings, breathing, and hearing for multiple cycles before they sleep.

How to Prevent Nightmares

The best way to prevent nightmares depends on why they are occurring. However, making certain lifestyle changes may help some individuals have fewer nightmares.

  • Prioritize sleep: Improving your sleep hygiene might prevent or reduce nightmares. Avoid alcohol, stimulants, and heavy meals before bedtime. Maintain a consistent sleep schedule and a relaxing evening routine.
  • Change medications: Many medications can cause nightmares. If you believe a medication is giving you bad dreams, be sure to talk to your doctor before changing your dosage or stopping the medication.
  • Talk to a professional: Do not hesitate to talk to a doctor or mental health professional if your nightmares are causing sleep problems. Sometimes, treating an underlying condition like depression, anxiety, or PTSD can reduce or eliminate nightmares altogether.
  • Explore cognitive behavioral therapy (CBT): Some people are able to prevent nightmares through CBT. CBT involves working with a therapist to change the thoughts and feelings that can trigger nightmares.

About The Author

Rebecca Levi

Staff Writer, Sleep Health

With a bachelor’s degree in anthropology from Indiana University Bloomington, Rebecca enjoys making accurate, up-to-date health information accessible to all readers. As a freelance writer and editor, she has covered everything from healthcare and experimental music to education. Rebecca lives in Tennessee, where she spends her free time reading, writing fiction, and making music.

  • POSITION: Side Sleeper
  • TEMPERATURE: Cold Sleeper
  • CHRONOTYPE: Dolphin

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