February 24, 2026, 9:59 am | Read time: 6 minutes
Every night, the brain immerses itself in a world of images, emotions, and fantasies, but in the morning, all that often remains of the dream world is a vague feeling. If you want to consciously remember your dreams, you can train yourself to do so. Experts explain exactly how this works.
It is no longer a secret that the brain remains active around the clock, even during sleep. But what actually happens in the brain while we dream? Depending on the sleep phase, different types of dreams can occur. Find out more about this and how you can better remember what you dreamed in the following article.
Overview of dreams
What Happens in the Brain When We Dream?
The term “dreaming” refers to a sequence of images, emotions, and feelings that occur during the so-called REM phase of sleep. The term REM stands for “rapid eye movements.” The human brain remains particularly active in this sleep phase—sometimes even more active than when awake.
Interesting fact: During REM sleep, neuronal connections—which, among other things, promote memory—are strengthened. In addition, hormones such as dopamine and serotonin are produced, which are important for learning processes and memory. REM sleep can therefore make you more attentive, focused, and balanced during the day.
In addition, the production of hormones ensures that our muscles temporarily relax. This is known as REM atonia. The relaxation of the muscles prevents dreams from being physically experienced. On average, we spend about two hours a night dreaming. The content of these dreams can allow conclusions to be drawn about everyday life. Some cultures regard dreams as divine warnings, messages, or spiritual explorations of the soul. In this context, they are sometimes also seen as a way of predicting evil spirits or even making contact with the deceased.1
Why Do People Dream Every Night?
The exact answer to this question has not yet been clarified. However, there are various theories that assume that dreams can help to integrate new experiences into memory or to process emotional experiences. Other explanations assume that dreams are a reaction to external stimuli that are perceived during sleep.
“In principle, all people dream when they sleep, otherwise something is wrong with the brain,” explains Prof. Michael Schredl, Scientific Director of the Sleep Laboratory at the Central Institute of Mental Health (ZI) in Mannheim.2 Some dreams are realistic and based on memories, while others are completely new, creative scenarios.
Different Sleep Phases, Different Dreams
The type of dream experience also varies greatly throughout the night. “This is due to the different cycles that the body goes through during sleep,” explains Dr. Alfred Wiater, former Chairman of the Board of the German Society for Sleep Research and Sleep Medicine (DGSM).3
After falling asleep, there is an initial phase of light sleep, followed by deep sleep, in which the body is particularly relaxed, and the brain works very little. “The dreams in these sleep phases are short and abstract,” explains Wiater.
It becomes more intense in REM sleep, which is characterized by rapid eye movements. “Dreams are most intense in REM sleep,” says the expert. This phase is characterized by particularly vivid and emotional dream content.
Dreams as a Mirror of Everyday Life
But what exactly do we dream about? Dreams are usually about events that have occupied us during the day. “It’s usually about what keeps you busy during the day,” says Schredl. This can include happy experiences, such as a planned trip, as well as stress or arguments at work.
Sometimes, however, dreams are completely detached from reality. “This shows how creative the brain sometimes is,” emphasizes Schredl. By dealing with dreams in particular, you can learn more about yourself—even if the content is stressful or frightening.
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What Are Nightmares?
Nightmares have many facets: you experience a fall into the depths, the loss of a loved one, or an escape from something threatening. These bad dreams, often known as “nightmares,” occur mainly in the REM sleep phase.
In most cases, however, they are harmless and merely lead to restless sleep. However, if they occur repeatedly over a long period of time and are perceived as particularly stressful by those affected, they can lead to health problems.
The question of why people have nightmares has not yet been answered. However, there are some factors that could contribute to the development of nightmares:
- Dementia
- Pregnancy: hormonal changes can be accompanied by intense emotions.
- Medication: such as antidepressants, sleeping pills, or antihypertensives, can also increase the frequency of nightmares
- Genetic factors
- Stress
- Mental illness and trauma: such as anxiety disorders, depression, or post-traumatic stress disorder (PTSD) have an influence on sleep behavior.
- Other risk factors: sleep disorders, lack of sleep, or an irregular sleep rhythm. Excessive drug or alcohol consumption can also contribute to the development of nightmares.4
Consciously Change Nightmares
As already mentioned, recurring nightmares can be a serious burden. “They are caused by a psychological disorder, but they are very treatable,” explains Dr. Annika Gieselmann from Heinrich Heine University Düsseldorf.5
According to experts, particularly persistent nightmares can become anchored in the memory as a fixed script and thus lose their original function of processing experiences. “It often helps to think about how the story of the nightmare can be changed so that it is no longer bad, either alone or with a confidant,” advises Gieselmann.
If these methods do not help, professional support may be useful. “The cause could then be a psychological stress disorder,” says Wiater.
What Do Nightmares Do to the Body?
It is during sleep and dreams that the human brain processes the experiences of the day. The limbic system, which is responsible for memory, learning processes, and emotions, is particularly active. The brain filters out unimportant information and processes all relevant events—including stressful aspects.
If you experience a nightmare, your muscle tension and heart rate increase enormously. Breathing also speeds up, and excessive sweating occurs. Emotions such as sadness, anger, or fear increase during the course of the dream.
Training the Memory of Dreams
Not everyone can remember their dreams—but this can be practiced. According to Schredl, it helps to make a conscious effort to remember the dream before going to sleep. Practical aids can also help: A notebook or dictaphone right next to the bed makes it easier to record dreams immediately after waking up.
Another technique is to repeat the dream to yourself over and over again as you wake up, similar to memorizing a poem. This helps you to remember the night’s mental movie better—and reveals exciting insights into your own world of thoughts.