How much sleep does a 4-month-old need?

Between 12 and 16 hours in 24 hours. Most 4-month-olds sleep 9–12 hours at night (often broken) and nap 3–5 hours across 3–4 naps during the day. The wide range reflects the significant variation in how severely the 4-month regression affects different babies.

Is the 4-month sleep regression real?

Yes — and unlike later regressions, it is permanent. At around 3.5–4 months the baby's sleep architecture changes permanently to resemble adult sleep, with multiple stages and more frequent surfacing between cycles. This is not a phase that passes on its own — it requires the baby to learn to settle independently between cycles. Without that skill, the frequent waking continues indefinitely.

My 4-month-old was sleeping well and is now waking every 45 minutes. What happened?

This is the 4-month regression. The sleep architecture change means the baby now surfaces between sleep cycles (approximately 45 minutes long) and, if they have a comfort association, calls for it to resettle. A baby who previously slept through was likely in a lighter, less-structured newborn sleep pattern that did not produce the same surfacing. The change is permanent — the resolution is teaching independent settling.

Should I sleep train my 4-month-old?

Four months is an appropriate age to begin teaching independent settling if you choose to. Most developmental paediatricians consider 4 months the earliest appropriate age for behavioural sleep approaches. The most important element is not which method you use but how consistently you apply it — inconsistency is more disruptive than any particular approach.

How many naps should a 4-month-old have?

Three to four. Most 4-month-olds take 3 longer naps and a short late-afternoon catnap to bridge to bedtime. The fourth nap drops naturally between 5 and 6 months as wake windows lengthen. If the baby is fighting the fourth nap, try pulling bedtime earlier rather than forcing the catnap.

What wake windows should a 4-month-old have?

Between 75 and 120 minutes. A 4-month-old waking at 7:00am should have their first nap around 8:15–8:30am. Wake windows at the end of the day are typically the longest — the final wake window before bed is often 1.75–2 hours. If the baby is taking a long time to settle at bedtime, the final wake window may be too short.

My 4-month-old only naps for 30 minutes. How do I extend naps?

Short naps at 4 months are almost universal and are caused by the same sleep cycle maturation that causes night waking. The most effective first step is improving overnight settling — when the baby learns to fall asleep independently at the start of the night, naps often improve without any direct nap intervention within 2–3 weeks.

When does the 4-month regression end?

The 4-month regression does not end on its own — the sleep architecture change it reflects is permanent. What does resolve is the disruption caused by the change, once the baby learns to settle independently between cycles. With a consistent approach, most families see significant improvement within 5–10 nights. Without any change to settling habits, many babies gradually improve over weeks to months as they mature, though the underlying association typically persists.

3.5–5 months

4 months

How much sleep, how many naps, what bedtime — and what's normal at this stage.

Total sleep

12–16 hrs

Night sleep

9–12 hrs

Naps

4 naps · 3–5 hrs

Bedtime

18:00–20:00

Sample 4 months schedule

Time	Activity
07:00	Wake + feed
08:15	Nap 1 (45–60 min)
09:15	Wake + feed
11:00	Nap 2 (1–1.5 hrs)
12:30	Wake + feed
14:15	Nap 3 (45–60 min)
15:15	Wake + feed
17:00	Nap 4 (30–45 min — catnap)
17:45	Wake + feed
19:00	Bedtime routine
19:30	Asleep

All times are approximate. Adjust by 30–60 minutes to suit your child.

What's normal at 4 months

•Three to four naps daily — the fourth is a short catnap
•The 4-month regression — frequent night waking, short naps, difficulty settling
•Wake windows of 75–120 minutes — longer than at 3 months
•Increasing awareness and distractibility during feeds
•Hands in mouth constantly — not necessarily hunger
•Rolling beginning — may disrupt sleep if unable to roll back
•Stronger sleep associations becoming apparent overnight

What changed since 0–3 months

•Sleep architecture has permanently changed — the baby now cycles through light and deep sleep in a pattern similar to adults, producing more frequent surfacing between cycles overnight
•Wake windows have lengthened from 45–90 minutes to 75–120 minutes
•The circadian rhythm is now established — a consistent bedtime is both possible and effective
•Sleep associations that were invisible in the newborn period now directly cause night waking — whatever the baby falls asleep with, they will look for between cycles
•The fourth trimester is over — the baby is now a biologically distinct sleep organism

What's coming next

Between 5 and 6 months the fourth nap drops for most babies as wake windows lengthen. This is also the optimal window for building independent settling skills — the sleep architecture is mature enough to respond to consistency, and the baby is not yet mobile enough for settling to be complicated by standing in the cot.

4-month sleep regression

Typically 3.5–5 months

The 4-month regression is not a temporary phase — it is a permanent neurological change. At around 3.5–4 months the baby's sleep architecture matures from the simple newborn pattern to an adult-like pattern with multiple stages including light, deep, and REM sleep. The baby now surfaces between each 45-minute cycle. In an adult this is imperceptible. In a baby with a comfort association (feeding, rocking, dummy), each surface produces a wake-up because the association is not present. The only resolution is teaching the baby to resettle independently.

Full guide: 4-month sleep regression →Full reset guide →

Common challenges at 4 months

Waking every 45 minutes overnight

The 45-minute night waking is the signature of the 4-month regression. The baby has learned to fall asleep with a prop (breast, bottle, rocking, dummy) and is now surfacing between cycles looking for that prop. The only lasting fix is separating the prop from sleep onset — the baby needs to learn to fall asleep independently at the start of the night so they can resettle the same way between cycles.

Short naps (the 45-minute nap)

Short naps at 4 months are caused by the same mechanism as night waking — the baby surfaces between sleep cycles and cannot link them. Unlike overnight, nap linking is harder to resolve without a more structured approach. The priority at this age is night sleep — when overnight settling improves, naps often follow within 2–3 weeks.

Rolling during sleep

Rolling to the front during sleep is common from around 4 months and is a significant source of parental anxiety. Current guidance: once a baby can roll both ways independently, they can be left to find their own sleep position. Before they can roll back, parents often need to make a judgement call about risk vs sleep disruption. A firm, flat mattress with no loose bedding is the non-negotiable foundation.

Feeding-to-sleep association

The feeding-to-sleep association that was harmless at 3 months now directly causes multiple night wakings at 4 months. The fix is to move the bedtime feed earlier in the routine so the baby is drowsy but awake when placed in the cot. This single change — separating feed from sleep onset — resolves a significant proportion of 4-month night waking within 5–7 nights.

Build your 4 months routine

Four months is the optimal time to build a sleep routine. The circadian rhythm is established, the baby responds to consistency, and sleep associations are not yet deeply entrenched. A structured approach now produces results in days, not weeks.

Build my routine — $45 →

Related guides

Questions about 4 months sleep

Methodology grounded in paediatric sleep research and evidence-based clinical practice. Schedule data, wake window recommendations, and regression timelines are derived from published guidelines including those of the American Academy of Sleep Medicine (AASM), the National Sleep Foundation, and paediatric sleep research published in peer-reviewed journals.

Read our full methodology →