Most babies start sleeping through the night around 3 to 6 months old, though “sleeping through the night” typically means a stretch of 6 to 8 hours, not the 10 or 11 hours adults might imagine. Some babies reach this milestone earlier, others much later, and the variation is completely normal. The timeline depends on a handful of biological developments that have to fall into place first.
What “Sleeping Through the Night” Actually Means
When pediatricians talk about a baby sleeping through the night, they mean a continuous stretch of roughly 6 to 8 hours. That’s it. A baby who goes down at 10 p.m. and wakes at 4 a.m. technically qualifies. This matters because many parents assume the goal is a baby who sleeps from 7 p.m. to 7 a.m. without a sound. That kind of sleep is not what most 3- or 6-month-olds are doing, and expecting it can make normal infant sleep feel like a problem.
Even adults wake briefly between sleep cycles. Babies do the same. The difference is whether they can drift back to sleep on their own or need help from a parent to resettle.
Why Newborns Can’t Do It Yet
Three things need to mature before a baby can sleep for long stretches: their internal clock, their stomach capacity, and their ability to self-soothe. Newborns have none of these in place.
A newborn’s stomach is tiny and empties quickly, so frequent feedings every 2 to 3 hours are a biological necessity. As babies grow over the first few weeks and months, their stomachs hold more milk at each feeding and the time between feedings gradually lengthens. This is why night feeds naturally space out on their own over time rather than disappearing all at once.
The internal body clock, or circadian rhythm, doesn’t even begin developing until around 2 to 4 months of age and isn’t fully established until at least 12 months, often later. Before that clock kicks in, babies have no biological distinction between day and night. Their sleep is scattered in short chunks around the clock, which is frustrating for parents but entirely expected.
Self-soothing is the third piece. Newborns simply don’t have the neurological capacity to calm themselves down. That ability starts to emerge around 3 months at the earliest, and emotional regulation continues developing for years. Before 3 months, a baby genuinely needs a caregiver to help them settle.
The 3- to 6-Month Window
Most babies begin sleeping 6 to 8 hours without waking around 3 months old. By this point, their circadian rhythm is starting to take shape, they can take in more milk per feeding, and their nervous system is beginning to allow brief self-soothing. For many families, this is when nights shift from survival mode to something more predictable.
That said, “most” is not “all.” Some babies get there at 2 months, and plenty of healthy, normally developing babies still wake at night well past 6 months. Breastfed babies tend to wake more frequently than formula-fed babies because breast milk digests faster, but this difference narrows over time as solid foods enter the picture.
If your baby hasn’t hit this milestone by 4 or 5 months, it doesn’t signal a problem. The range of normal is wide, and the biological systems driving sleep consolidation mature on their own schedule.
Sleep Regressions and Setbacks
Even after your baby starts sleeping longer stretches, expect some backsliding. Sleep regressions are periods when a baby who had been sleeping well suddenly starts waking more often. They’re temporary, usually lasting a few days to a few weeks, and they’re tied to predictable developmental changes.
The first major regression hits around 4 months, right when a baby’s sleep patterns are shifting from newborn-style sleep to more adult-like sleep cycles. This one can feel especially brutal because it often coincides with the period when parents thought they’d finally turned a corner.
Around 8 to 9 months, separation anxiety becomes a factor. Babies at this age start understanding that you exist even when you leave the room, which is a cognitive leap forward but also means they protest more when you’re not there at 2 a.m. Other common triggers for regressions include teething pain, growth spurts that create extra hunger, learning a new physical skill like rolling over or pulling up (babies sometimes want to practice at night), and illness.
Regressions are not a sign that something went wrong with your baby’s sleep habits. They’re a sign of normal brain development, and they pass.
Breastfed vs. Formula-Fed Babies
Breastfed babies often take longer to sleep through the night. Breast milk is digested in about 90 minutes, while formula takes closer to 3 to 4 hours, so breastfed infants genuinely get hungry more often. In the early months, night feedings also help maintain a mother’s milk supply, so eliminating them too early can create a separate problem.
By 6 months, as babies begin eating solid foods and their caloric needs shift, the gap between breastfed and formula-fed sleep patterns tends to narrow. If you’re breastfeeding and your baby still wakes once or twice at night at 5 or 6 months, that’s within the range of normal.
What You Can Do to Help
You can’t force a baby’s biology to mature faster, but you can set up conditions that make longer sleep more likely once your baby is ready.
- Establish a day-night distinction early. Expose your baby to natural light during the day and keep nighttime feedings dim and quiet. This helps their developing circadian rhythm calibrate faster.
- Put your baby down drowsy but awake. Starting around 3 to 4 months, placing your baby in their crib when they’re sleepy but not fully asleep gives them a chance to practice falling asleep independently. This skill is what allows them to resettle on their own when they wake between sleep cycles.
- Create a consistent bedtime routine. A short, predictable sequence of events (bath, feeding, book, bed) signals to your baby that sleep is coming. The routine itself matters more than the specific activities.
- Gradually shift night feedings. Rather than cutting night feeds abruptly, you can slowly reduce feeding time or volume so your baby adjusts to taking in more calories during the day.
When Night Waking Lasts Longer Than Expected
Some perfectly healthy babies continue waking at night past their first birthday. Circadian rhythms aren’t fully mature until 12 months or later, and individual temperament plays a real role. Babies who are more alert, more sensitive to stimulation, or more socially aware of their caregivers tend to wake more often.
Persistent night waking becomes worth investigating if your baby seems to have trouble breathing during sleep, snores loudly, or is excessively sleepy during the day despite getting what seems like enough total sleep. These can point to airway issues that disrupt sleep quality regardless of how long the baby stays in bed. Frequent waking paired with poor weight gain is another combination worth raising with your pediatrician, since it could indicate the baby isn’t getting enough nutrition during the day.
For the vast majority of families, though, night waking in the first year is not a medical issue. It’s a developmental phase with a wide timeline, and your baby will get there.