Most babies start sleeping through the night around 6 months of age, though “through the night” at that stage means five to six hours of uninterrupted sleep, not the eight or more hours adults expect. Some babies get there as early as 4 months. The path to longer stretches of sleep depends on your baby’s biological readiness, their daytime feeding, the sleep environment, and the habits you build around bedtime.
Why Newborns Can’t Sleep Through the Night
Babies are born without a functioning internal clock. The circadian system that tells adults to feel sleepy when it’s dark and alert when it’s light simply isn’t online yet. Newborns don’t produce their own melatonin, and they lack stable cortisol rhythms, which is why their sleep looks so scattered in the early weeks. One case study found that when a breastfed infant was exposed only to natural light, a recognizable sleep-wake rhythm emerged around day 45, with nighttime sleep onset aligning with sunset by day 60. But for most families in modern lighting conditions, a reliable day-night pattern takes longer to develop.
Until that circadian system matures, your baby genuinely cannot distinguish night from day. This isn’t a habit problem or something you’re doing wrong. It’s biology. The most helpful thing you can do in the first two to three months is expose your baby to natural daylight during waking hours and keep nighttime feeds dim and boring. You’re giving the circadian system the light-dark signals it needs to calibrate.
Building a Bedtime Routine
A consistent bedtime routine is one of the most reliably effective tools for improving infant sleep. A large study of more than 10,000 children ages 0 to 5 found that having a bedtime routine was associated with earlier bedtimes, faster sleep onset, longer nighttime sleep, fewer night wakings, and fewer parent-reported sleep problems. The routine doesn’t need to be elaborate. It just needs to be predictable and happen in roughly the same order during the hour before lights out.
The activities that show up consistently in the research fall into four categories: nutrition (a final feeding), hygiene (a bath), communication (reading a book, singing), and physical contact (massage, cuddling, rocking). In one study, children who received a brief massage before sleep fell asleep faster and resisted bedtime less than children who were read a story instead. Music played before sleep also shortened the time it took children to fall asleep. You don’t need all of these every night. Pick three or four that work for your family and repeat them in order. The consistency is what signals to your baby that sleep is coming.
The Role of Daytime Feeding
There’s a persistent idea that if you just feed your baby more before bed, they’ll sleep longer. The reality is more nuanced. Research shows that infants who received more milk or solid food during the day were less likely to feed at night. That’s the good news. The catch: those babies were not less likely to wake. Daytime calories can reduce nighttime hunger, but waking up at night happens for many reasons beyond an empty stomach.
This means two things for you. First, making sure your baby gets full, frequent feeds during the day is genuinely helpful. If your baby is eating well during waking hours, they’re less likely to need a feed at 2 a.m. Second, if your baby is eating plenty during the day and still waking, the solution probably isn’t more food. It’s helping them learn to resettle without your intervention.
Sleep Training Methods
Sleep training typically starts working within about a week, and the research consistently shows it’s both effective and safe. A study of 235 infants (average age 7 months) found that sleep training cut severe sleep problems from 14% to 4%, and the number of babies waking twice or more per night dropped from 60% to 31%. Parents in the sleep training group also reported better mood, less fatigue, and improved sleep quality of their own. A separate trial following families for two years found no adverse effects on children and fewer depression symptoms in mothers.
The most studied approach is graduated extinction, sometimes called the Ferber method. The basic idea: put your baby down drowsy but awake, leave the room, and if they cry, wait two to five minutes before briefly checking in. You don’t pick them up. You offer a quick reassurance and leave again, extending the interval by a few minutes each time until they fall asleep. The first night or two can be rough. Most families see significant improvement by nights three through five.
If that feels too intense, gentler approaches exist. You can stay in the room and gradually move your chair farther from the crib over the course of a week or two. You can pick up and soothe your baby when they cry, then put them back down once calm. These methods tend to take longer but still work. The core principle across all approaches is the same: your baby needs opportunities to practice falling asleep without being held, rocked, or fed to sleep. Whatever method you choose, consistency matters more than which specific technique you use.
Catching the Right Sleep Window
An overtired baby is, paradoxically, harder to get to sleep. When babies stay awake past the point of comfortable tiredness, their stress hormones spike and they become wired, fussy, and resistant to settling. Learning your baby’s early tired cues helps you start the bedtime routine before you hit that wall.
Early signs of tiredness include turning away from you, staring off into space, and slower, less coordinated movements. As a baby moves past tired into overtired, you’ll see louder than usual crying, clenched fists, frantic arm and leg movements, and sometimes self-soothing behaviors like sucking on their hands. If your baby is arching their back and screaming, you’ve likely missed the window by 15 to 20 minutes. Tracking when your baby naturally gets drowsy for a few days can help you find the sweet spot and build your routine around it.
Setting Up the Sleep Environment
The recommended room temperature for infant sleep is 68 to 72°F (20 to 22°C). A room that’s too warm is both a sleep disruptor and a safety concern. Dress your baby in one layer more than you’d wear comfortably in the same room, and skip the blankets entirely for the first year.
For safety, the sleep surface should be firm, flat, and covered only with a fitted sheet. Nothing else goes in the crib: no pillows, stuffed animals, bumpers, blankets, or weighted swaddles. Babies should sleep on their backs, in their own crib or bassinet, in the same room as a parent. Bed sharing, couch sleeping, and sleeping in car seats or swings as a regular habit all increase risk. If your baby falls asleep in a car seat or stroller, move them to their crib as soon as you can.
Darkness matters too. A truly dark room supports melatonin production. If you need a nightlight for middle-of-the-night feeds, use one with a warm or red tone rather than a bright white or blue light, which suppresses the sleep signals your baby’s brain is still learning to produce.
Sleep Regressions Are Normal
Even babies who have been sleeping well will hit rough patches. These regressions tend to cluster around developmental milestones. The most common one happens around 4 months, when your baby’s sleep architecture is maturing and cycling between lighter and deeper stages for the first time. A baby who had been sleeping long stretches may suddenly start waking every two hours.
Later regressions often coincide with new physical skills. A baby who just learned to pull up to standing may wake at night and practice in the crib, then cry because they can’t figure out how to lie back down. Around 9 months, separation anxiety peaks, and your baby may protest being alone in the crib more intensely. Teething, illness, growth spurts, and travel can all disrupt sleep temporarily too.
Regressions typically last one to three weeks. The most helpful response is to stay as consistent as possible with your bedtime routine and sleep expectations while being responsive to genuine needs like hunger or illness. Babies who had good sleep habits before a regression generally return to them once the developmental surge passes, as long as new habits (like bringing them into your bed or feeding them to sleep every waking) haven’t taken root in the meantime.
Realistic Expectations by Age
At 0 to 3 months, your baby will wake frequently and that’s completely normal. Focus on establishing day-night patterns through light exposure, not on sleep training.
At 4 to 5 months, some babies begin sleeping five to six hour stretches. This is when a consistent bedtime routine starts to pay off. If your baby is still waking frequently and you’re struggling, this is the earliest most pediatricians consider sleep training appropriate.
At 6 to 9 months, most babies are biologically capable of sleeping through the night without a feed. This is the window where sleep training tends to be most effective. Expect some disruption around 8 to 9 months from separation anxiety and new motor skills.
At 9 to 12 months, nighttime sleep typically consolidates further. Babies who are still waking multiple times at this age often have a learned association (nursing, rocking, being held) that they need help breaking. The same sleep training principles apply, and they work just as well at this age as they do at 6 months.