Why Is REM Sleep Important? Dreams, Memory, and Emotions
What research shows about REM sleep, why it matters for dreams, memory and emotions, how much REM adults typically get, and what can disrupt this sleep stage.
Key takeaways
- REM stands for Rapid Eye Movement. It is a normal stage of sleep characterized by active brain patterns, rapid eye movements and reduced muscle tone.
- REM is associated with memory and emotional processing. Researchers are still studying its exact functions and how it interacts with other sleep stages.
- Vivid dreams are common during REM. However, dreaming can also occur during non-REM sleep.
- REM periods usually become longer later in the night. Cutting sleep short can reduce the time available for these later periods.
- More REM is not automatically better. Adequate sleep duration, continuity and overall sleep quality matter more than achieving a particular percentage on a tracker.
In this article
- What Is REM Sleep?
- What Happens in the Brain and Body During REM?
- Why Is REM Sleep Important?
- Why Do We Dream During REM Sleep?
- How Much REM Sleep Do We Need?
- When Does REM Sleep Occur During the Night?
- What Happens When REM Sleep Is Disrupted?
- What Can Reduce or Disrupt REM Sleep?
- Can We Increase REM Sleep?
- Frequently Asked Questions
- Final Thoughts
We spend part of every night in REM sleep, a stage associated with vivid dreams, active brain patterns and changes in how the body responds to movement.
Researchers have also connected REM sleep with memory and emotional processing. But that doesn’t mean REM works alone or that getting more of it automatically makes you healthier.
So why is REM sleep important, how much do we normally get, and what happens when it is interrupted? Understanding this stage can help explain why a full night’s sleep matters more than simply spending enough hours in bed.
What Is REM Sleep?
REM means Rapid Eye Movement, referring to the characteristic eye movements that occur beneath closed eyelids during this stage of sleep.
Sleep includes three non-REM stages, called N1, N2 and N3, followed by REM. These stages recur throughout the night rather than occurring only once.
N3 is medically classified as deep sleep, while REM is a separate stage in which brain activity can resemble wakefulness, even though the person is asleep.[1]
Our guide to the four stages of sleep explains the complete sleep cycle. For a closer comparison of their functions, see deep sleep vs. REM sleep.
What Happens in the Brain and Body During REM?
REM sleep is unusual because the brain becomes highly active while most skeletal muscles are temporarily inhibited.
During REM, several changes typically occur:
- Brain activity increases: Electrical patterns measured during REM can resemble those recorded while awake.
- The eyes move rapidly: These movements are one of the characteristics used to identify REM sleep.
- Muscle tone decreases: Most voluntary muscles are temporarily inhibited, a phenomenon called REM atonia.
- Breathing and heart rate become more variable: Their patterns can be less regular than during some non-REM stages.
Because of the contrast between an active brain and reduced muscle movement, REM is sometimes called paradoxical sleep.
What Is REM Atonia?
REM atonia is the normal reduction in muscle tone that occurs during REM. It helps prevent most physical movements associated with dream activity.
For example, you might dream about running while your body remains largely still.
In REM sleep behavior disorder, this normal inhibition can be disrupted, and a person may act out parts of their dreams. Repeated shouting, punching, kicking or other potentially dangerous movements during sleep deserve medical assessment.
Why Is REM Sleep Important?
REM appears to contribute to several processes associated with normal brain function. Memory and emotional processing are among the most widely studied, although researchers have not established a single explanation for every function of REM.
REM Sleep and Memory Consolidation
Memory consolidation is the process through which newly acquired information becomes more stable and is integrated with existing knowledge.
Research suggests that REM may participate in certain types of learning and memory, particularly the processing of emotionally meaningful experiences. Studies have found associations between REM brain activity and the retention of emotional information.[4]
However, it would be inaccurate to say that REM alone stores memories. Non-REM sleep also contributes to memory consolidation, and different stages may support different aspects of learning.
The precise contribution of REM remains an active research question. Some experimental results support a role in memory, while others are more difficult to interpret because disrupting REM can also alter stress levels or overall sleep quality.
REM Sleep and Emotional Processing
REM has also been studied in relation to emotional memories and the way the brain responds to emotionally significant experiences.
One influential hypothesis, proposed by researchers including Matthew Walker and Els van der Helm, suggests that the particular neurobiological conditions of REM may influence how emotional memories are reprocessed during sleep.[5]
This does not mean REM automatically removes stress or makes upsetting memories less emotional.
A 2024 systematic review found growing evidence linking REM disruption with aspects of emotional processing, but also emphasized that experimental methods vary and human studies remain limited.[7]
It is therefore reasonable to describe REM as a potential contributor to emotional memory processing, while recognizing that the mechanisms and consequences are not fully understood.
Why Do We Dream During REM Sleep?
Vivid, elaborate dreams are especially common during REM sleep. The brain remains active, and networks involved in perception, memory and emotion participate in this sleep state.
However, dreaming does not occur exclusively during REM. People can also report dreams after being awakened from non-REM sleep.
Scientists have proposed several explanations for dreaming, including ideas involving memory, emotional experiences and spontaneous brain activity. No single hypothesis fully explains why all dreams occur.
Dream research also has a practical limitation: researchers usually learn about dream content from what participants remember and describe after waking.
REM and dreaming are strongly associated, but dreaming should not be considered the only purpose of REM sleep.
How Much REM Sleep Do We Need?
There is no official recommendation stating that everyone needs a particular number of REM minutes each night.
In adults, REM commonly accounts for approximately 20–25% of total sleep time, although normal variation occurs.
The amount of REM can change with age, total sleep duration, medications, alcohol use and certain sleep disorders.
For example, if an adult sleeps eight hours, 20–25% would correspond to approximately 96–120 minutes of REM. This is an illustration of a typical proportion, not an individual target or a requirement to measure each night.
Instead of focusing only on a REM percentage, it is more useful to consider how sleep quality is measured, including total sleep time, interruptions and how rested you feel during the day.
Can a Smartwatch Measure REM Sleep Accurately?
Smartwatches and fitness trackers estimate sleep stages using signals such as movement and heart rate. Some also use changes in heart rate variability and other measurements.
These devices do not usually record the full set of signals used in clinical sleep studies. Their estimates may therefore misclassify individual sleep stages.
In contrast, polysomnography records brain activity, eye movements, muscle activity and additional physiological signals. These measurements help clinicians identify REM and non-REM stages more directly.
A smartwatch showing 15% REM on one night does not establish that you have a REM deficiency. If you have persistent daytime sleepiness, unusual nighttime behaviors or other significant sleep symptoms, clinical assessment is more useful than relying on a single tracker result.
When Does REM Sleep Occur During the Night?
REM sleep occurs repeatedly during a typical night rather than being concentrated in one continuous period.
According to the National Heart, Lung, and Blood Institute, sleep cycles usually repeat approximately every 80–100 minutes, and people commonly experience four to six cycles each night.[1]
The first REM period often begins approximately 90 minutes after falling asleep, although timing varies. Early REM periods tend to be relatively short, while later ones generally become longer.
Deep N3 sleep is usually more prominent during the earlier part of the night. REM becomes more prominent toward morning.
This distribution matters because regularly cutting sleep short can reduce the time available for later REM-rich cycles.
Our guide to how much sleep you really need explains why sleep duration and regularity both matter for normal sleep.
What Happens When REM Sleep Is Disrupted?
Researchers have investigated how experimentally reducing or interrupting REM affects learning, memory and emotional responses.
Some studies have found changes in emotional processing and particular memory tasks following REM disruption. However, results are not completely consistent, and experimentally interrupting REM can also increase stress or disturb other aspects of sleep.[7]
It is also important to distinguish reduced REM from insufficient sleep overall.
Regularly sleeping too little can affect:
- Attention and concentration
- Memory and learning
- Emotional regulation
- Decision-making
- Reaction time and daytime alertness
These problems should not automatically be attributed to REM alone. Insufficient sleep also reduces or disrupts other important stages.
What matters most is allowing adequate time for the normal sequence of sleep stages to occur.
What Can Reduce or Disrupt REM Sleep?
Several factors can change sleep architecture, meaning the organization and distribution of sleep stages throughout the night.
Alcohol
Alcohol may initially make a person feel sleepy, but it can alter the normal distribution of sleep stages and contribute to fragmented sleep later in the night.
Its effects on REM depend on factors including the amount consumed and the timing relative to sleep.
Certain Medications
Some medications, including certain antidepressants, can affect REM timing and duration.
For example, many antidepressants increase the time before REM begins and reduce the amount of REM recorded during sleep. These effects differ between medications and individuals.[8]
This does not mean that these medicines are harmful because they alter REM. Their clinical benefits and risks must be considered as a whole.
Do not stop or change prescribed treatment to increase REM sleep. Any medication concerns should be discussed with the prescribing healthcare professional.
Sleep Schedule and Frequent Awakenings
Irregular schedules, frequent awakenings, noise, uncomfortable sleeping conditions and certain sleep disorders can interrupt the normal progression through sleep stages.
Light exposure also affects circadian timing. The body’s natural melatonin rhythm helps signal biological night, although melatonin should not be understood as a supplement that selectively increases REM.
Conditions such as sleep apnea can fragment sleep repeatedly, making clinical assessment important when symptoms suggest a breathing-related sleep disorder.
Can We Increase REM Sleep?
There is no reliable, generally recommended method for selectively increasing REM sleep in healthy adults.
Trying to maximize REM is also not the same as improving overall sleep health. The body normally moves through different stages, and each contributes to sleep’s broader functions.
Practical habits that can support more regular and sufficient sleep include:
- Keep a reasonably consistent schedule. Regular sleep and wake times help support circadian alignment.
- Allow enough time for sleep. Cutting sleep short limits opportunities for later sleep cycles.
- Create a comfortable sleep environment. A dark, quiet room can help reduce unnecessary awakenings.
- Be physically active during the day. Regular activity can support overall sleep health.
- Pay attention to evening habits. Bright light, alcohol and irregular bedtime routines may interfere with normal sleep.
Our guide to red light and sleep explains how different lighting conditions may influence sleep timing without making unsupported claims about increasing REM.
If you experience persistent insomnia, loud snoring, breathing pauses, severe daytime sleepiness or repeated unusual movements during dreams, speak with a healthcare professional rather than trying to change REM percentages yourself.
Frequently Asked Questions
Why Do You Sometimes Wake Up During a Vivid Dream?
Vivid dreams are common during REM sleep. When you wake during or shortly after a dream, the experience may still be available in memory, making it easier to recall. If you continue sleeping, the memory of the dream may fade. However, waking from a vivid dream does not prove that the awakening itself was caused by REM, and dreams can also occur during other sleep stages.
Can Antidepressants Change REM Sleep?
Yes. Some antidepressants can delay the first REM period or reduce total REM duration, while effects differ among medications. These changes do not automatically mean the treatment is damaging sleep or memory. The benefits and side effects of medication must be considered together. Never stop antidepressants abruptly or alter your prescription to increase REM without medical guidance.
Does More REM Sleep Always Mean Better Sleep?
No. A higher REM percentage does not automatically indicate better sleep. The balance of sleep stages varies with age, medications, overall sleep duration and other factors. A higher percentage can also occur because the amount of another stage has changed. For everyday sleep health, adequate duration, continuity and how you function during the day are more meaningful than trying to maximize a single stage.
Final Thoughts
REM is a distinct stage of sleep associated with vivid dreams, active brain patterns and processes related to memory and emotions. Researchers continue to investigate its precise functions and how they interact with non-REM sleep.
Instead of trying to increase REM through supplements or sleep-tracking targets, focus on allowing enough time for regular, minimally interrupted sleep. Healthy sleep depends on the full pattern of sleep stages, not on maximizing one percentage.
References
- National Heart, Lung, and Blood Institute. How Sleep Works: Sleep Phases and Stages. NHLBI, NIH.
- National Heart, Lung, and Blood Institute. Your Guide to Healthy Sleep. NHLBI, NIH.
- National Institute of Child Health and Human Development. What Happens During Sleep? NICHD, NIH.
- Nishida M, Pearsall J, Buckner RL, Walker MP. REM Sleep, Prefrontal Theta, and the Consolidation of Human Emotional Memory. Cerebral Cortex, 2009. Scientific article.
- van der Helm E, Walker MP. Sleep and Emotional Memory Processing. Sleep Medicine Clinics, 2011. PubMed.
- Gujar N, McDonald SA, Nishida M, Walker MP. A Role for REM Sleep in Recalibrating the Sensitivity of the Human Brain to Specific Emotions. Cerebral Cortex, 2011. PubMed.
- The Effect of REM-Sleep Disruption on Affective Processing: A Systematic Review of Human and Animal Experimental Studies. Neuroscience & Biobehavioral Reviews, 2024. PubMed.
- TribI GG, et al. Dreaming Under Antidepressants: A Systematic Review on Evidence in Depressive Patients and Healthy Volunteers. Sleep Medicine Reviews, 2013. PubMed.
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