Most babies start sleeping through the night somewhere between 4 and 6 months old, but “sleeping through the night” doesn’t mean what most parents think it means. It doesn’t mean 10 or 12 uninterrupted hours. In medical terms, it typically refers to a stretch of 6 to 8 hours without needing a feeding. By that standard, roughly 72% of 12-month-olds sleep six or more consecutive hours at night. The rest don’t, and that’s still normal.
What “Sleeping Through the Night” Actually Means
New parents often picture a baby who goes down at 7 p.m. and doesn’t make a sound until morning. That’s not the clinical benchmark, and expecting it too early sets you up for frustration. A baby who sleeps from 11 p.m. to 5 a.m. without a feeding is, by pediatric standards, sleeping through the night. All babies wake briefly between sleep cycles, just like adults do. The difference is whether they can settle themselves back to sleep or whether they need you to help.
This distinction matters because it changes the question. You’re not really asking when your baby will stop waking up at all. You’re asking when they’ll stop needing you every time they wake.
Why Newborns Can’t Sleep Long Stretches
A newborn’s stomach holds about 20 milliliters at birth, roughly four teaspoons. A feeding of breast milk that size empties from the stomach in about one hour. That’s why newborns eat so frequently and why expecting any kind of long sleep stretch in the first weeks is biologically unrealistic. Their bodies are designed for frequent, small feedings around the clock.
Over the first few months, stomach capacity grows steadily, and babies begin taking in more calories per feeding. By around 3 to 4 months, most babies can take in enough at each feeding to sustain them for longer periods. Their circadian rhythm, the internal clock that distinguishes day from night, also starts maturing around this time. These two changes together create the biological foundation for longer stretches of nighttime sleep.
The 4-to-6-Month Window
For many families, the shift happens between 4 and 6 months. This is when babies begin consolidating their sleep into longer nighttime blocks and shorter daytime naps. Their sleep architecture changes too. Before 4 months, babies cycle between only two stages of sleep. Around 4 months, they transition to the same four-stage sleep cycle adults have, which means they briefly surface between cycles more often. Some babies adapt to this seamlessly. Others struggle with it, which is why the so-called 4-month sleep regression is so common.
The American Academy of Pediatrics notes that starting at 4 months, you can begin putting babies down when they’re drowsy but still awake. This helps them practice falling asleep independently, which is the core skill behind sleeping through the night. A baby who learns to fall asleep without being held or rocked is more likely to resettle on their own when they wake between sleep cycles at 2 a.m.
By 6 months, it’s normal for a baby to wake during the night and go back to sleep within a few minutes without any help. If your 6-month-old fusses briefly at 3 a.m. and then quiets down, that’s not a problem. That’s the skill working.
Why Some Babies Take Longer
Sleep development in infants is highly variable. Some 4-month-olds sleep eight hours straight. Some 12-month-olds still wake twice a night. Both can be perfectly healthy. Several factors influence where your baby falls on this spectrum.
- Feeding method. Breastfed babies tend to wake more often than formula-fed babies in the early months because breast milk digests faster. This difference usually narrows by 6 to 9 months.
- Temperament. Some babies are naturally more alert and reactive to changes in their environment, making it harder for them to stay settled through the night.
- Growth spurts and developmental leaps. Periods of rapid physical or cognitive growth often disrupt sleep temporarily, even in babies who were previously sleeping well.
- Separation anxiety. This peaks around 9 months and can cause a baby who had been sleeping independently to suddenly protest being put down or to cry when they wake and realize you’re not there.
Sleep regressions are less tied to specific ages than many parents assume. They’re more closely linked to whatever developmental milestone your baby is currently working through, whether that’s rolling over, crawling, pulling to stand, or processing new social awareness. These regressions are temporary, usually lasting two to four weeks.
What You Can Do at Each Stage
In the first three months, your goal isn’t to get your baby to sleep through the night. It’s to start building the cues that help them distinguish day from night. Keep daytime feedings bright and social. Keep nighttime feedings dim and quiet. This helps their circadian rhythm develop on schedule.
From 4 months on, you can begin encouraging independent sleep. The simplest version of this: put your baby in their crib drowsy but awake, and give them a few minutes to settle before stepping in. You don’t have to commit to a formal sleep training method. Even small, consistent changes in how you respond to nighttime waking can make a measurable difference over a few weeks.
Between 6 and 12 months, most babies are physiologically capable of going the night without a feeding. If your baby is growing well and your pediatrician confirms they don’t need overnight calories, nighttime wake-ups at this age are more about habit and comfort than hunger. This is the age range where sleep training methods, if you choose to use one, tend to be most effective.
What’s Normal at 12 Months
By a baby’s first birthday, the majority are sleeping through the night by the six-consecutive-hours definition. But about 28% of 12-month-olds still aren’t hitting that mark consistently. If your one-year-old wakes once or twice a night, you’re not doing anything wrong, and neither are they. The trend toward longer, more consolidated nighttime sleep continues well into the toddler years for some children.
What matters more than hitting a specific milestone by a specific month is the overall trajectory. If your baby is gradually sleeping longer stretches, waking less often, and learning to resettle more quickly, they’re on track, even if their timeline doesn’t match the one in the baby books.