Four months can be hard: a baby who was sleeping well suddenly wakes every 45 minutes. Let's go through the norms, the schedule and what actually helps — and separately, what part of the “four month regression” is confirmed and what is not.
| Metric | Norm | Note |
|---|---|---|
| Number of naps | 3–4 naps | Usually 3 longer ones + 1 short |
| Nap length | 30–90 min | Catnaps of 30–45 min are normal |
| Wake window | 1.5–2 hours | Between waking and the next sleep |
| Longest stretch without a feed | 3–5 hours | May be shorter when breastfeeding |
| Bedtime | 7:00–8:30 pm | Too late a bedtime means overtiredness |
A wake window is the time from waking up to the next time you put the baby down. At 4 months it is 1.5–2 hours. This is the key parameter of the day: put the baby down too early and they will not fall asleep, too late and they get overtired and settling becomes even harder.
| Age | Wake window | Naps per day |
|---|---|---|
| 3 months | 1–1.5 hours | 4–5 naps |
| 4 months | 1.5–2 hours | 3–4 naps |
| 5 months | 2–2.5 hours | 3 naps |
| 6 months | 2–3 hours | 2–3 naps |
This is a reference point, not a rigid timetable. Shift everything by 30–45 minutes depending on when the baby wakes in the morning.
Sleep architecture really does reorganise in the first months: the share of deep sleep grows, the share of REM falls. But this is gradual maturation across two years, not an event of one week, and it does not map onto a date. The claim “at 4 months the architecture changes for good, and that is why the regression happens” is a retelling, not a measurement; the detailed analysis with sources is in a separate article.
What is true and useful: a baby's sleep cycle is short, and at the transition between cycles they partially wake. If they can fall asleep on their own, they settle and sleep on. If not, they call you. This explains short naps at any age, with no connection to four months.
That is the length of one sleep cycle. The baby moves from deep sleep into light sleep and surfaces for a second. Adults do the same but can fall back asleep without waking. A baby cannot, if their falling-asleep habit is tied to an external cue (breast, rocking).
There is one solution: help the baby learn to fall asleep without outside help. That does not have to mean “cry it out” — gentle methods of gradually dropping the association exist.
Yes. One or two night feeds at 4 months are physiologically normal. There is no need to try to drop night feeds before 5–6 months. But if there are 5–7 of them, that is most likely not hunger but a habit of settling by sucking.
If the baby wakes after 45 minutes and is content, that is their norm. If they cry and want to sleep on, try coming into the room 5 minutes before the usual waking and putting a hand on their tummy at the moment of the cycle transition. Or use the pram or a carrier for a longer nap.
At 4 months a rhythm built on wake windows works better than one built on the clock. Watch for tired signs and go by 1.5–2 hours of awake time. In one or two months the rhythm will become more stable.
Nobody knows, and the common “4–8 weeks” has no source — we could not find the study it could come from. Instead of counting weeks, look at the daily sleep total and at how the baby feels, and rule out illness first.
Yes, and you should — by 4 months rolling begins, and tight swaddling becomes dangerous (risk of SIDS if the baby rolls onto their front). Options: 1) gradually — free one arm first, the second after 3–5 days; 2) at once — replace the swaddle with a sleeveless sleep sack. The first nights may be worse because of the Moro reflex; it passes in 5–10 days.
At 4 months gentle methods work best: Pick-up/Put-down (Tracy Hogg) — put the baby down drowsy, pick up for 30 seconds if they cry, put back; the Chair method — sit next to the cot, moving further away every three days. Harder methods (cry-it-out) — not before 5–6 months.
No, that is a popular myth. Sleep depends on the settling skill, the rhythm and wake windows — not on the amount of food. The WHO recommends starting solids at 6 months. At 4 months it is early: the gut is not ready and the allergy risk is higher.
Age is not the deciding factor here: there is no “one right window” in the calendar. What matters are the conditions: the baby is healthy, there are no other changes (a move, a trip, going back to work), and you are ready to hold the approach for several weeks in a row. If sleep got worse suddenly and for no clear reason, it is wiser to rule out illness and wait a few days than to start training in the middle of an unstable week.
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