Your baby's eyes are half-open during sleep, unfocused and still. Is that normal? What the science says about physiological lagophthalmos in infants, and when to check with a pediatrician.
You lean over the crib to check on your sleeping baby, and their eyes are half-open — still, unfocused, staring at nothing. The instinct is immediate: is this normal? Should you wake them, or leave them be? Here is what the science says, question by question.
Baby sleeps with eyes open: is it normal?
Yes, in the vast majority of cases. A newborn's eyelid muscles are still immature and don't always close fully during sleep, especially during active sleep. This has a medical name — lagophthalmos — and it is common, temporary, and not a sign of a problem in an otherwise healthy, developing baby.
It's usually when a parent leans in close that this detail becomes visible — and alarming, even though it goes unnoticed most of the time. Some babies sleep with their eyes open continuously for several minutes; others only intermittently, sometimes with one eye open while the other stays closed. Both patterns fall within the normal range.
What is physiological lagophthalmos in infants?
Lagophthalmos simply means the eyelids don't close all the way during sleep. In adults, it's sometimes linked to a medical cause — facial nerve damage, certain thyroid conditions. In a healthy infant, it comes from an entirely different and benign mechanism: pure muscular immaturity.
Pediatric sources call this physiological or nocturnal lagophthalmos of infancy: a baby can sleep with eyes intermittently open without ever needing help closing them to keep sleeping normally, and without it reflecting facial nerve damage, a thyroid issue, or any of the adult-context causes. That distinction matters — a very young baby's still-developing nervous system has nothing to do with the causes of lagophthalmos seen in adults.
Why a baby's eyelids don't fully close during sleep
This drop in tone affects the whole body — it's part of what makes sleep restorative — but in an infant whose eyelid musculature isn't yet fully developed, it can leave the eyes partly open underneath the lids.
Lire aussi
Muscle tone drops during active sleep, and the eyelid muscles are no exception.
The gaze, in these moments, stays unfocused and distant: the baby isn't looking at or tracking anything. You may notice small, rapid eye movements under the partly-open lids — a hallmark of REM sleep. That's a useful cue for telling this normal phenomenon apart from a real awakening, when the gaze sharpens and starts following a face or object. Quiet sleep, by contrast, usually comes with fully closed eyelids and near-complete stillness — this behavior shows up mostly during active sleep.
What the science says — why this is more common in babies than adults
A newborn spends a much larger share of sleep in active sleep — the infant equivalent of REM sleep in adults — which is exactly why this is so much more visible and frequent in babies. A study following 42 full-term infants with polysomnography across their first five weeks of life measured this proportion directly (Wielek et al., 2019).
In adults, REM sleep typically makes up 20 to 25% of total sleep time — far lower than in newborns. The study measured active sleep at 60.6% of total sleep time at 2 weeks of age, dropping slightly to 57.2% by 5 weeks. That high share of active sleep goes a long way toward explaining why so many parents notice this in their baby, and so rarely in an older sibling or adult in the same household.
It's precisely during this active sleep phase — marked by more irregular breathing, small body movements, and that same body-wide drop in muscle tone, eyelids included — that a baby's eyes are most likely to stay partly open.
At what age does this fade?
The share of active sleep gradually decreases over the first months, and eyes-open sleep episodes naturally become less common. This tracks the broader maturation of sleep cycles, which consolidate night after night over the first year, with a growing share of quiet sleep as months go by.
Most parents notice a clear drop-off around 6 months, and many babies close their eyes more consistently at night by around 9 months — without there being one hard milestone to hit. Some babies keep occasionally sleeping with eyes half-open past that age, and another family member sometimes did the same as a child; that kind of family pattern is, on its own, not meaningful.
Simple steps if the eyes look irritated or dry
In the overwhelming majority of cases, no special action is needed. A baby's eyes resting under partly-open lids aren't exposed to ambient air the way a fully open eye is during the day, and true dry-eye irritation is genuinely rare in an otherwise healthy infant.
If you do notice redness or unusual discharge in the morning, a few simple steps help limit irritation: keep the room at a reasonable humidity, avoid direct drafts on the baby's face during sleep, and gently wipe around the eyes with a damp, clean cloth if needed.
When to see a pediatrician
See a pediatrician if the eye discomfort looks real — persistent redness, unusual discharge, excessive blinking on waking — or if something about this behavior worries you long-term. Those are the signs that warrant medical input, not the simple fact that a baby's eyes stay partly open during sleep.
A pediatrician can rule out local irritation and, if needed, refer you to a pediatric ophthalmologist for a persistent concern. There's never a wrong reason to bring this up at a routine visit — it's one of the topics parents are least likely to ask about, even though it's extremely common.
A trend-tracking device like Mothair follows movement, heart rate, and breathing night after night — measurable physiological signals, distinct from visually observing the eyes, and no substitute for a pediatrician's opinion on this specific topic.
Important: Mothair is a wellness device and is not a medical device. It does not diagnose anything and does not replace a pediatrician's advice. This article is for informational purposes. For any medical question about your baby, consult your pediatrician.
FAQ
Is it normal for a baby to sleep with eyes open?
Yes, it's common and usually harmless: an infant's still-immature eyelids don't always close fully, especially during active sleep. This is called physiological lagophthalmos.
Why don't a baby's eyelids close all the way during sleep?
During active (REM) sleep, muscle tone drops throughout the body, including the eyelids, which can leave the eyes intermittently and partly open, sometimes with small visible eye movements.
At what age does this usually go away?
The share of active sleep gradually decreases over the first months, and most babies close their eyes more consistently at night by around 6 to 9 months.
Should I see a pediatrician if my baby's eyes look dry or irritated?
Yes — if you notice redness, dryness, or visible discomfort, a pediatric visit can rule out irritation that needs treatment.
The bottom line
A baby sleeping with eyes partly open is, in the vast majority of cases, a sign of normal active sleep — not a warning sign, and not the same as the pathological lagophthalmos described in adults. It comes down to immature eyelids and a newborn's large share of REM sleep, and it fades naturally with age. Only real signs of eye irritation warrant a pediatrician's input.
To learn more about infant sleep cycles, see our guide on active vs. quiet sleep by age.
Discover Mothair
The connected sensor under the sheet that watches over your baby's breathing and sleep, contact-free.
