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Baby handbook

Sleep from 4 to 6 months

Sleep4 min read

Longer nights start to appear, and the famous 4-month shift is a brain change, not a failure.

Somewhere around 4 months, sleep changes in a way that startles families who had just found a rhythm. The baby who gave you a five-hour stretch may start waking every two hours again. That shift has a name in parenting circles and a plainer description in sleep science: infant sleep is reorganizing into lighter and deeper cycles, closer to the pattern adults have. It is a developmental step. It is not proof that you created a bad habit in week twelve.

What the numbers look like now

From about 4 to 12 months, total sleep often lands around 12 to 16 hours, with 12 to 15 hours a common quoted range. More of it consolidates at night. A stretch of 6 to 8 hours becomes possible for some babies. Others still wake to eat, and that can be appropriate, especially for babies who are nursing and growing quickly. Night weaning is a family and clinician decision, not a deadline that arrives on the 4-month birthday.

Naps are usually three or four across the day. Wake windows stretch toward 1.5 to 2.5 hours. The first window of the morning is often the shortest, and the one before bed the most fragile. A baby who is awake for three hours in the late afternoon may unravel even if the morning went well.

The 4-month shift, without the drama

Before this age, babies drop into deep sleep more easily and stay there. After it, they surface between cycles, about every 40 to 60 minutes at night and sometimes at the 30-minute mark of a nap. If the way they fell asleep is gone when they surface, they call for help recreating it. That might be a feed, a bounce, or a hand on the chest. All of those are reasonable responses. The change is that the surfacing is new, so the help is requested more often.

Short naps, especially a reliable 30 to 45 minute nap, are common through this whole stretch. The brain is practicing linking cycles. You can give it a week of trying to resettle once before assuming the nap is over. If resettling never works, end the nap, offer a feed if it is time, and try again at the next window. Chronic overtiredness makes the next nap shorter, so protecting bedtime is often more productive than chasing a perfect midday stretch.

A sample day

Block Often looks like
Wake Feed, play, nap about 1.5 to 2 hours after waking
Midday Feed, play, second nap
Afternoon Feed, play, a shorter third nap. A fourth nap is still normal for some 4-month-olds.
Evening Feed, a short wind-down, bed. Many babies do well with an earlier bedtime during this shift, sometimes 6:30 to 7:30.
Night One or more feeds. A long first stretch is a good sign, not a requirement.

Bedtime can include a short, repeatable sequence: diaper, sleep sack, a song, lights out. The sequence is a cue. It does not have to last 40 minutes, and it does not have to happen in a silent house.

Rolling, swaddles, and the crib

This is the age when rolling shows up, sometimes overnight. Stop swaddling as soon as your baby can roll onto their side or stomach. Move to a sleep sack with the arms free. If they roll in the crib after you placed them on their back, and the crib is bare, you do not have to flip them back all night. Start every sleep on the back.

The room-sharing recommendation from the AAP still applies: baby nearby, on their own firm flat surface, for at least 6 months. A crib in your room counts. A pillow in your bed does not.

How much help to give

There is no single correct way to respond to night waking at 4 to 6 months. Some families feed at every wake. Some pause for a minute to see if the baby resettles, then feed if the cry builds. Some are working with a clinician on a more structured plan because a caregiver is returning to work and the current pattern is not sustainable. All of those can be loving. What does not help is a plan that leaves you so depleted you are unsafe, or a plan that ignores hunger in a baby who still needs night calories.

If you change something, change one thing and hold it for several nights. Switching from feeding to rocking to driving around the block in the same evening teaches nothing except that the evening is chaotic. A boring, repeatable response is easier for everyone to learn.

When sleep is a medical question

Snoring every night, pauses in breathing, or a baby who always sleeps with the neck extended and still seems to work for air should be seen. So should very little daytime weight gain, fewer wet diapers, or a new rash with fever. Ordinary 4-month waking is miserable and common. Breathing that looks wrong is not something to coach through.

Sources

This guide is general information for families, not medical advice, and it is not a substitute for your pediatrician.

This Baby handbook page is general information, not medical advice. When in doubt, call your pediatrician.