REM Sleep and Dreams: Why You Dream, and Why You Remember Some Dreams

Almost everyone has woken from a dream so vivid it took a few seconds to remember where they were. Those dreams usually come from REM sleep, the stage of sleep when your brain is at its most active. Understanding the link between REM sleep and dreaming can make your nights feel a little less mysterious, and it can help you understand why your dreams change when your sleep changes.

This article covers what happens in the brain during REM sleep, what scientists do and do not know about why we dream, why some dreams stick and others vanish, and when dreams or nightmares are worth raising with a professional.

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What REM sleep is

REM stands for rapid eye movement. During this stage your eyes dart back and forth behind closed eyelids, your breathing and heart rate become less regular, and brain activity rises to levels that look surprisingly similar to being awake. At the same time, most of your voluntary muscles become temporarily relaxed, a state often called REM atonia. That built-in pause is thought to stop you from physically acting out your dreams.

REM sleep usually first appears about 60 to 90 minutes after you fall asleep, then returns at the end of each sleep cycle. The REM periods get longer as the night goes on, so the final hours before you wake contain the most REM. If you want the full picture, start with what REM sleep is.

Do you only dream in REM sleep?

No. People can dream in non-REM sleep too, and researchers who wake people from different stages in the lab get dream reports from all of them. But dreams from REM sleep tend to be different. They are more likely to be long, emotional, visual and story-like, the kind of dream you would describe to someone at breakfast. Dreams from non-REM sleep are more often short, thought-like or fragmentary.

So while it is not accurate to say REM sleep is the only time you dream, it is fair to say REM sleep is when most of your vivid, memorable dreams happen.

Why do we dream?

This is one of the big open questions in sleep science, and there is no single agreed-upon answer. Several ideas have research support, and they are not mutually exclusive:

• Memory processing. One leading idea is that dreaming reflects the brain sorting, linking and consolidating memories. Dreams often borrow fragments from recent days mixed with older memories.
• Emotional processing. REM sleep is linked with processing emotional experiences. Some researchers suggest dreaming helps take the sharp edge off difficult emotions over time.
• Threat rehearsal. Another theory proposes that dreams let us simulate challenging or threatening situations in a safe setting.
• A by-product of brain activity. Some scientists argue dreams are partly the mind’s attempt to make a story out of the brain activity happening during REM sleep.

The honest summary is that dreaming probably reflects several processes at once, and the research is still evolving. Be cautious of any website or product that claims to know exactly what your dreams mean.

Why you remember some dreams and not others

Most people dream every night, even if they rarely remember it. Whether a dream sticks seems to depend on a few things.

When you wake up

You are much more likely to remember a dream if you wake up during or right after REM sleep. Since REM periods are longest in the early morning, a dream right before your alarm is the one you are most likely to recall.

How quickly you get up

Dream memories fade quickly. If you jump out of bed and start checking your phone, the dream often disappears within minutes. Lying still for a moment and replaying the dream helps it stick.

How often you wake during the night

People who wake briefly more often during the night tend to report more dreams. That is not necessarily a good thing. Frequent waking can be a sign of fragmented sleep from noise, heat, stress or other factors.

Interest and attention

People who are interested in their dreams, or who keep a dream journal, generally report remembering more of them. Paying attention appears to help.

Why dreams get more intense sometimes

Many people notice phases where their dreams become unusually vivid or strange. Common reasons include:

• REM rebound. After a period of short sleep, your brain tends to make up for lost REM sleep, which can bring intense dreams. Read more in our guide to REM rebound.
• Stopping alcohol. Alcohol suppresses REM sleep. When people cut back, REM can return strongly for a while, along with vivid dreams. See alcohol and REM sleep.
• Stress and big life changes. Emotional events often show up in dreams. See stress and REM sleep.
• Medications. Starting, stopping or changing some medications can affect dreams. Always talk to your prescriber before making changes.
• Sleeping later than usual. Sleeping in gives you extra REM-heavy time in the morning, which can mean more dreams.

Nightmares: when are they a problem?

Occasional bad dreams are normal and common in both children and adults. They often follow stress, illness, or a disrupted schedule.

Nightmares become worth discussing with a doctor or therapist when they happen often, cause distress, make you afraid to go to sleep, or follow a traumatic experience. There are effective, evidence-based treatments for frequent nightmares, including a form of therapy called imagery rehearsal therapy. You do not have to just put up with them.

Acting out dreams is different

Normally the muscle relaxation of REM sleep keeps you still while you dream. In a condition called REM sleep behavior disorder, that relaxation does not work properly, and people can shout, punch or kick during dreams. This is different from ordinary sleep talking or restless sleep, and it deserves a medical evaluation, especially in adults over 50. Our page on REM sleep behavior disorder explains the warning signs.

Lucid dreaming

A lucid dream is a dream where you become aware that you are dreaming, and sometimes can influence what happens. Lucid dreams are most often reported during REM sleep. Some people experience them naturally, and others try techniques like reality checks during the day or briefly waking and going back to sleep in the early morning.

If you are curious about lucid dreaming, it is generally fine to explore it casually. Avoid techniques that require repeatedly cutting your sleep short, since that can leave you short on overall sleep.

Can you improve your dreams by improving your REM sleep?

You cannot choose your dreams, but you can support healthy REM sleep, which supports normal dreaming. The basics are the same ones that help sleep in general:

• Allow enough time in bed so you reach the long REM periods near morning. Most adults need at least seven hours.
• Keep a consistent wake-up time to anchor your body clock. See sleep schedule.
• Keep alcohol modest and away from bedtime.
• Keep your bedroom cool, dark and quiet. See sleep environment and how sleep temperature affects REM sleep.
• Build a calm wind-down routine to reduce stress before bed.

How to remember more of your dreams

If you want to recall more dreams, try these simple steps:

1. Before sleep, remind yourself that you want to remember your dreams.
2. Keep a notebook or notes app by the bed.
3. When you wake, stay still for a minute with your eyes closed and replay what you remember.
4. Write down anything, even a single image or feeling. Details often come back as you write.
5. Do this for a couple of weeks. Most people find recall improves with practice.

Dreams across the lifespan

Babies spend a much larger share of their sleep in REM, or the active-sleep stage that resembles it, than adults do, and the proportion gradually falls through childhood. Children often report simpler dreams, and nightmares are particularly common in young kids. In adulthood, the share of REM sleep tends to stay fairly stable, although overall sleep often becomes lighter and more broken with age, which can change how often people wake during dreams.

Older adults sometimes notice they remember fewer dreams. That can reflect changes in sleep patterns rather than a lack of dreaming. Our guide to REM sleep by age covers how sleep shifts over a lifetime.

A note on dream interpretation

Dream dictionaries and symbol guides are popular, but there is little scientific evidence that specific dream images carry fixed meanings. A more grounded approach is to notice the emotions in your dreams and how they relate to what is happening in your waking life. If a recurring dream keeps bothering you, talking it through with a therapist can be more useful than any symbol list.

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