Your baby was sleeping great — and suddenly everything fell apart. Waking every 45 minutes. 3-hour bedtime battles. You're not doing anything wrong. This is what's called the 4 month sleep regression. What is established and what is not, right below; what actually helps in those weeks, further down.
| Parameter | Normal at 4 months | Note |
|---|---|---|
| Number of naps | 3–4 naps | Usually 3 longer + 1 short "bridge" |
| Wake window | 1.5–2 hours | Between wake and next nap |
| Nap duration | 30–90 min | 45 min naps are very common now |
| Bedtime | 7:00–8:30 PM | Earlier is better during regression |
So this page is about sleep at four months, not about a scheduled event. Many babies do have a harder stretch somewhere around this age; many do not. Below are the norms, the typical patterns and what helps — none of which depends on whether the difficulty has a name.
Wake windows — time between waking up and going back to sleep — are the key to the whole schedule. At 4 months: 1.5–2 hours. Miss the window and your baby becomes overtired, which makes everything worse.
| Age | Wake window | Number of naps |
|---|---|---|
| 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 |
| Time | Activity |
|---|---|
| 7:00 AM | Wake, feed, play |
| 8:45 AM | Nap 1 (45–90 min) |
| 10:00 AM | Feed, play, tummy time |
| 11:45 AM | Nap 2 (45–90 min) |
| 1:15 PM | Feed, play, outing |
| 3:00 PM | Nap 3 (45–60 min) |
| 4:00 PM | Feed, calm play |
| 5:30 PM | Nap 4 short "bridge" (30 min max) |
| 6:30 PM | Bedtime routine: bath, feed, song |
| 7:30 PM | Night sleep |
That's the length of one sleep cycle. At the transition point, your baby briefly surfaces. Adults do this too, but we learned to go back to sleep without fully waking. Your baby hasn't — yet. The fix is helping them learn to transition independently.
Nobody knows, and the figures that circulate — 4–8 weeks — have no study behind them that we could find. Rather than counting weeks, watch the 24-hour sleep total and your baby's wellbeing — and rule out illness first.
Sleep architecture really does mature during infancy — that much is established. A worsening tied specifically to four months is not: no peer-reviewed study shows such a peak, and measurements show sleep consolidating fastest between 1 and 4 months. Difficult stretches at this age are real; the calendar behind the name is not.
Often yes. But at 4 months, a baby over 5kg doesn't physiologically need multiple night feeds. Increased nursing is usually comfort-seeking, not hunger. Addressing the sleep association is more effective than just feeding through it.
Baby Sleep Planner calculates the exact moment to put your baby down based on their age and sleep history. No more guessing.
Try free for 7 days