The rhythmic motion of the pram trundling over paving stones is a proven method of getting a tired baby to sleep. For some babies they fall into a deeper sleep rapidly, allowing you to stop wheeling and they will stay asleep. This was my experience with my son, he would be fast asleep as soon as we left the house. I could then go shopping or even grab a coffee with him contently snoozing next to me.
Every baby is different of course, but it was still a shock when my daughter came along and she fought sleeping in the day at every opportunity! She would be exhausted and grumpy and it would take half an hour of traipsing the streets to get her to sleep. Worse than that, if I had to stop for a moment, even to cross the road, she would wake instantly and that would be that. It was the same in the car, I used to dread stopping at lights!
So why do some babies sleep better when the pram is moving? One theory is that babies who are rocked to sleep in their parents’ arms associate the rhythmic motion with sleep time. I don’t think this was the case with my children as we never rocked them at night time so that association wasn’t there. Some sleep experts suggest that the motion reminds the baby of being in the womb and feeling the movement of mum moving about during the day. Either way the motion works and babies tend to drift off and remain asleep longer if the pram is moving.
You might also find this interesting: Tips on how to get a baby to sleep more quickly in the pram