Everyone dreams. You spend about 2 hours each night dreaming but may not remember most of your dreams. Its exact purpose isn’t known, but dreaming may help you process your emotions. Events from the day often invade your thoughts during sleep, and people suffering from stress or anxiety are more likely to have frightening dreams. Dreams can be experienced in all stages of sleep but usually are most vivid in REM sleep. Some people dream in color, while others only recall dreams in black and white.
Medically Reviewed by
Dr. Alex Dimitriu
Dreams are one of the most fascinating and mystifying aspects of sleep. Since Sigmund Freud helped draw attention to the potential importance of dreams in the late 19th century, considerable research has worked to unravel both the neuroscience and psychology of dreams.
Despite this advancing scientific knowledge, there is much that remains unknown about both sleep and dreams. Even the most fundamental question — why do we dream at all? — is still subject to significant debate.
While everyone dreams, the content of those dreams and their effect on sleep can vary dramatically from person to person. Even though there’s no simple explanation for the meaning and purpose of dreams, it’s helpful to understand the basics of dreams, the potential impact of nightmares, and steps that you can take to sleep better with sweet dreams.
What Are Dreams?
Dreams are images, thoughts, or feelings that occur during sleep. Visual imagery is the most common1, but dreams can involve all of the senses. Some people dream in color while others dream in black and white2, and people who are blind tend to have more dream components related to sound, taste, and smell3.
Studies have revealed diverse types of dream content, but some typical characteristics of dreaming include:
It has a first-person perspective.
It is involuntary.
The content may be illogical or even incoherent.
The content includes other people who interact with the dreamer and one another.
It provokes strong emotions.
Elements of waking life are incorporated into content.
Although these features are not universal, they are found at least to some extent in most normal dreams.
Why Do We Dream?
Debate continues among sleep experts4 about why we dream. Different theories5 about the purpose of dreaming6 include:
Building memory: Dreaming has been associated with consolidation of memory, which suggests that dreaming may serve an important cognitive function of strengthening memory and informational recall.
Processing emotion: The ability to engage with and rehearse feelings in different imagined contexts may be part of the brain’s method for managing emotions.
Mental housekeeping: Periods of dreaming could be the brain’s way of “straightening up,” clearing away partial, erroneous, or unnecessary information.
Instant replay: Dream content may be a form of distorted instant replay in which recent events are reviewed and analyzed.
Incidental brain activity: This view holds that dreaming is just a by-product of sleep that has no essential purpose or meaning.