Most parents start getting longer stretches of sleep around the three-month mark, when babies begin sleeping six to eight hours without waking. But “sleeping through the night” doesn’t mean your baby sleeps ten uninterrupted hours. It means longer consolidated blocks, which for an exhausted parent can feel transformative even if it’s not a full night’s rest. The full picture is more nuanced than a single milestone, and knowing what to expect month by month can make the wait feel less endless.
The First 12 Weeks: The Hardest Stretch
Newborns don’t have a functioning internal clock. Their circadian rhythm, the biological system that tells us to sleep when it’s dark and wake when it’s light, develops piece by piece over the first few months of life. A cortisol rhythm appears around eight weeks, melatonin production kicks in at roughly nine weeks, and body temperature patterns settle around eleven weeks. Until those systems come online, your baby genuinely cannot tell the difference between day and night.
This means the first six to eight weeks are the most fragmented period of sleep you’ll experience. Newborns sleep in short bursts of two to four hours, eat, and go back down regardless of what the clock says. For you, that translates to broken sleep around the clock. Research using wrist-worn activity monitors found that sleep fragmentation roughly doubles in the first two weeks after delivery compared to late pregnancy, and sleep efficiency doesn’t begin recovering until about ten to twelve weeks postpartum.
Around weeks nine through twelve, things start to shift. As your baby begins producing melatonin, a diurnal pattern emerges: more sleep at night, more wakefulness during the day. This is the biological turning point most parents are waiting for.
Months 3 Through 6: The Improvement Window
By three months, most babies are capable of sleeping a six-to-eight-hour stretch at night. That doesn’t mean every baby will, but the biological machinery is in place. You may find yourself waking up startled at 4 a.m. not because the baby is crying but because you’re surprised they haven’t.
This period also comes with a well-known disruption: the four-month sleep regression. As babies mature, their sleep architecture changes from mostly deep sleep to cycling between deep and light phases, similar to adult sleep. That transition can cause a baby who was sleeping beautifully to suddenly wake up multiple times a night. It’s temporary, and it’s a sign of normal neurological development, but it can feel brutal after you’d finally started getting longer stretches. Additional regressions can pop up around growth spurts and developmental milestones throughout the first year, though they don’t follow a fixed schedule for every child.
What “Sleeping Through the Night” Actually Means
The clinical definition is surprisingly modest. Pediatricians generally consider a baby to be sleeping through the night when they manage a six-to-eight-hour block. That’s it. A baby who goes down at 8 p.m. and wakes at 2 a.m. technically qualifies. So if you’re measuring your progress against images of a baby sleeping peacefully from 7 p.m. to 7 a.m., you’re setting a target most babies won’t hit for many more months.
Reframing this expectation matters because it changes how you feel about your own situation. If your four-month-old is doing a five-hour stretch followed by a quick feed and another three-hour stretch, you’re much closer to the finish line than it feels at 3 a.m.
How Feeding Method Affects Your Sleep
One of the most common questions new parents ask is whether formula feeding leads to better sleep. The answer is more complicated than the advice you’ll hear from other parents. A 2024 study tracking infants from six to thirty-six months found no significant difference in total sleep duration over 24 hours between breastfed and formula-fed babies. Breastfed babies did wake more frequently at six and twelve months, meaning their sleep was more fragmented, but by 24 months there was no measurable difference.
In practical terms: formula-fed babies may give you slightly longer uninterrupted blocks in the early months, but the total amount of sleep your baby gets in a day is roughly the same regardless of feeding method. If you’re breastfeeding and feeling pressure to switch for the sake of sleep, the evidence suggests the difference is real but smaller than most people assume, and it fades entirely by the second year.
Your Body’s Own Recovery Timeline
Even when your baby starts sleeping longer stretches, you may find that your own sleep doesn’t immediately bounce back. After months of fragmented rest, many parents report difficulty falling asleep, lighter sleep, or waking at odd hours even when the baby is quiet. This is partly habit and partly biology. The hormonal environment after delivery changes significantly: estrogen levels decline steadily across the first seventeen weeks postpartum, and prolactin remains elevated during breastfeeding. These shifts can affect sleep quality independent of how often your baby wakes you.
The good news is that objective measures of sleep efficiency, how much of your time in bed is actually spent sleeping, tend to recover around ten to twelve weeks postpartum. Your body is remarkably good at recalibrating once given the opportunity. The subjective feeling of being rested takes longer, partly because you’re running a sleep debt that built up over weeks or months.
A Realistic Month-by-Month Outlook
- Weeks 0 to 6: Expect the most disrupted sleep of the entire experience. Two-to-four-hour blocks are normal. Survival mode is appropriate.
- Weeks 6 to 12: Your baby’s circadian rhythm is forming. Night stretches start lengthening. You may get one four-to-six-hour block on good nights.
- Months 3 to 4: Many babies hit six-to-eight-hour stretches. The four-month regression may temporarily undo this progress.
- Months 5 to 6: Sleep patterns typically restabilize. Many parents describe this as the period where they finally feel functional again.
- Months 6 to 12: Sleep generally continues improving, with occasional disruptions around teething, illness, and developmental leaps. By the end of the first year, most babies sleep ten to twelve hours at night with one or two naps during the day.
What You Can Control Right Now
You can’t speed up your baby’s circadian development, but you can support it. Exposing your baby to natural light during the day and keeping nighttime feedings dim and quiet helps reinforce the difference between day and night. This doesn’t produce instant results, but it gives the developing circadian system the right environmental cues.
For safe sleep, the American Academy of Pediatrics recommends placing babies on their backs in their own sleep space, on a firm, flat mattress with a fitted sheet and nothing else. No loose blankets, pillows, stuffed animals, or bumpers. Avoid letting babies sleep on couches, armchairs, or in swings and car seats outside of the car. Following these guidelines reduces the risk of sleep-related infant death and also means you’re not staying awake out of worry about an unsafe sleep setup.
Sleep when the baby sleeps is cliché advice because it’s genuinely hard to follow, but front-loading your own rest in the evening can help. If your baby’s longest stretch starts at 8 p.m., going to bed at 8:30 instead of 11 captures hours of sleep you’d otherwise lose. Splitting night duties with a partner, even informally, so that each person gets one protected four-to-five-hour block can be the difference between coping and not coping during those early weeks.