Why does what used to help suddenly stop working?

Rocking always worked. The stroller always worked. And now suddenly they don't, while you're doing exactly the same thing.

This happens with most babies around the third and fourth month.

What has changed

Two things at once.

The senses have gotten sharper. Your baby sees, hears and feels much more than a month ago, and that suddenly makes sleeping harder. Where in months one and two your baby dozed off anywhere, in the stroller or in a busy restaurant, all of that now comes in.

The practicing has begun. In the first months, your baby needed you to calm down. Now your baby is constantly experimenting with how to do it alone. It doesn't fully work yet, but small steps are being taken, and that's impressive work.

How that practicing works

There's a circle behind it. Overstimulation comes, you comfort, and your baby feels the calm. The brain remembers that feeling and goes looking for how to get there alone. That repeats, again and again, and that's how a skill grows.

So your comforting isn't the opposite of self-regulation. It's the source of it.

What you can see

See if you recognize any of these:

• Rolling from one side to the other, or turning onto the side.
• Turning the head away when going to sleep.
• Quickly pulling the legs up and dropping them again.
• Very deliberately sucking on hands or fingers.
• Looking for a familiar lovey.

That last one is a good thing to start now. Both of Kyra's daughters went looking for their bunny from about four months, and a familiar thing like that makes the surroundings feel safer. You introduce a lovey by offering it while comforting, so it becomes part of calming down. See also learning to self-soothe.

What this asks of the sleep space

Now that the senses are wider open, the surroundings weigh more. A dark room, the right temperature, familiar sounds: from now on that makes more difference than before. See setting up the nursery.

Practically, because you have a life too: do the first nap at home in the familiar setting. That's usually the easiest nap of the day. The afternoon naps are harder, because a lot has already happened by then, and that's exactly when movement helps: the carrier, the stroller, the car. That way enough daytime sleep still gets in.

And this is where your bedtime routine suddenly gets more powerful. The little steps are really recognized now: into the room, curtains closed, lights down, softer voices, white noise on. That's exactly what you'll need later.

Your role now: observe and don't force anything

Give room to practice. That means something uncomfortable: don't step in too fast. If you comfort right away, or try something else within half a minute, your baby has no chance to discover anything alone.

Experiment with new ways of comforting, but give each try time. See also how to calm your baby.

When it's something else

If the restlessness stays high, with a lot of crying, excessive arching of the back, or pushing feeds away, get help. Talk to your pediatrician or a lactation consultant: something else may be going on, like reflux, an allergy or a digestive problem.