What is the 4 month sleep regression?

Your baby slept stretches of four hours, sometimes six. And from one week to the next, it's every forty-five minutes, sometimes after an hour, sometimes after an hour and a half. You haven't changed anything. You're doing everything the same.

That's the 4 month sleep regression, and the word regression is misleading. Nothing is going backwards. Something big is happening.

What's going on in that little head

Before four months, your baby was a deep sleeper. Barking dogs, a sibling stomping through the room, a car alarm: your baby slept right through it.

Around four months comes the switch from spectator to participant. Not just watching the world anymore, but joining in: grabbing, responding, recognizing. And so much more comes in during a day.

All those new impressions have to be processed, and that happens in REM sleep, dream sleep. So suddenly a lot more of it is needed.

And that's exactly where the problem lies.

Why the night breaks open

At the end of every sleep cycle, your baby briefly comes almost to the surface. An adult turns over and sleeps on without noticing. That's a skill, and it isn't there yet.

The REM and non-REM phases can't be linked smoothly yet. So what follows is real waking, no more relaxing, and crying to look for comfort. Once, twice, sometimes as many as five times a night.

That's not a bad habit and not a step back. Something new is being learned.

Kyra's step-by-step plan

Four steps, and they repeat.

1. Wait

Don't go in right away. Listen to the cry first. Babies sometimes cry while linking sleep cycles, so if you come in at that moment and add stimulation, you wake your baby all the way up. Then it gets harder instead of easier.

Five to ten minutes, depending on your baby and on the moment. There's no fixed number. You don't have to wait ten minutes; above all, you have to listen for a bit.

2. Calm

If the crying gets worse instead of less, go in calmly. Pick up, rock, walk a little, or simply lay your hand on your baby. What works differs per baby. The goal is to calm the nervous system, not to get your baby to sleep.

3. Give space

Put your baby back in the crib while still awake, and stay in the room. Sit next to the crib, so your baby can feel you're there. But don't take over. This is the moment you see whether your baby can manage alone.

4. Repeat

If the protest continues, you go back, calm, and put down again. Calm and predictable. The same every time.

About night feeds

Almost every parent feeds more in this phase, simply because it works and it's the middle of the night.

That's allowed. Kyra is clear about it: if you've tried everything and it's not working, feeding is fine. It's your choice and your night.

To be honest about it, though: feeding at this moment can become a strong sleep association. Your baby then looks for the feed to get back to sleep, and you wean that later. That's possible, calmly and step by step, once the phase is over.

What you don't need to fear: that you're now teaching something you'll never get rid of. That's not how it works.

How long it lasts

Your baby's body clock is only fully developed around six months. Four months is an important point on the way, not an end point. During this period, help make the difference between day and night clearly felt: light and movement during the day, dark and quiet at night.

And be kind to yourself. For many parents this phase coincides with going back to work. It's exhausting, and that it's exhausting doesn't mean you're doing it wrong.

If the evening gets stuck in this period too, look at the hours before it. An overstimulated baby goes into the night already tense, and then the regression isn't your only problem.

And once this phase is over, the question often comes whether it's time for sleep coaching. That doesn't depend on age but on three things that need to be in place first.

Is the regression over and are you wondering whether that 3 a.m. feed is still needed, read how to drop night feeds step by step. First the day, then the night.

What else is normal for sleep in that month is in how much sleep a 4 month old needs.