Infants probably don’t dream the way you’d expect. Despite spending roughly half their sleep time in a REM-like state, most sleep researchers believe newborns lack the cognitive machinery to produce the vivid, story-like dreams adults experience. What’s happening in their brains during all that active sleep is fascinating, but it looks very different from dreaming as we understand it.
Why So Much REM but Likely No Dreams
Newborns sleep about 16 hours a day, and roughly half of that time is spent in active sleep, the infant version of REM. For comparison, adults spend only about 20 to 25 percent of their sleep in REM. That massive gap is the first clue that infant REM serves a different purpose than adult REM.
In adults, REM sleep is when most dreaming happens. But the psychologist David Foulkes, who spent decades studying children’s dreams at the University of Wyoming, argued that true dreaming, the kind with active storylines where you see yourself as a character, doesn’t reliably appear until children are between 7 and 9 years old. His reasoning: dreaming requires a level of self-awareness and spatial imagination that the infant brain simply hasn’t built yet. You need to mentally picture yourself in a scene, understand that “you” exist as a separate person moving through space, and construct a narrative. A newborn can’t do any of that.
This doesn’t mean nothing is happening in a sleeping baby’s brain. It means the brain is busy doing something else entirely.
What Active Sleep Actually Does for Babies
If infants aren’t dreaming during all those hours of REM-like sleep, what’s going on? The leading theory is that active sleep is when the developing brain wires itself together. During active sleep, sensory feedback from the baby’s own body movements activates brain circuits, helping to build and strengthen neural pathways throughout the nervous system.
Think of it as a self-testing system. The brain sends signals that cause small twitches and movements, then processes the sensory information that comes back. This loop helps calibrate everything from motor control to sensory processing. Premature babies as young as 28 to 31 weeks gestational age already show recognizable periods of active sleep with continuous brain activity, suggesting this wiring process begins well before birth.
Brain wave recordings during infant active sleep show a pattern called activité moyenne: continuous, low-to-medium voltage mixed-frequency activity that actually looks similar to the brain waves seen during normal wakefulness. The brain is “on” during active sleep, just not producing dreams.
Those Smiles and Twitches Aren’t What They Seem
It’s hard to watch a sleeping baby smile and not assume they’re having a pleasant dream. But researchers believe those smiles are spontaneous rather than responses to dream imagery. Studies show that newborns sometimes produce complex facial expressions during REM sleep before they even make those same expressions while awake. Their first smile may actually happen during sleep, not in response to a parent’s face.
One key difference between infant active sleep and adult REM: adults are temporarily paralyzed during REM so they don’t act out their dreams. Infants aren’t. During active sleep, babies freely twitch, jerk their limbs, make sucking motions, smile, and frown. Researchers believe these spontaneous smiles help develop the facial muscles needed for later social smiling and laughter. The movements are essentially practice runs for skills the baby will use when awake.
So when your newborn grins in their sleep, the most likely explanation isn’t a happy dream. It’s the brain rehearsing the mechanics of smiling itself.
When Real Dreams Begin
The shift from brain-building sleep activity to actual dreaming is gradual and tracks with cognitive development. Very young children, when woken from REM sleep in lab studies, typically report either nothing or brief, static images (a dog standing still, for example) rather than narratives. The complex, story-driven dreams adults recognize don’t consistently show up until around age 7 to 9, when children develop stronger spatial reasoning and reflective self-awareness.
Nightmares can start earlier than full narrative dreaming. Children may begin having nightmares as young as 6 months, though these peak between ages 3 and 12. Whether a 6-month-old experiences a nightmare the same way a 5-year-old does is unclear. At that age, a “nightmare” may be closer to a distressing sensory experience than a coherent scary story.
How to Tell What Sleep Stage Your Baby Is In
You can distinguish active sleep from deep sleep just by watching. During active sleep (the REM-like stage), you’ll notice twitching arms and legs, fluttering eyelids, irregular breathing, facial expressions, and small body movements. Breathing may pause for 5 to 10 seconds, then resume with a burst of rapid breaths before settling back to a regular rhythm. This pattern is normal.
During deep non-REM sleep (quiet sleep), all that twitching and movement stops. Breathing becomes steady and even. The baby is harder to wake. A full newborn sleep cycle lasts about 45 to 60 minutes and includes both stages, which is why you might see your baby shift from still and peaceful to squirmy and grimacing and back again in under an hour.
The active phases aren’t signs of distress or bad dreams. They’re signs of a brain doing exactly what it’s supposed to do: building itself, one twitch at a time.