The 4-month sleep regression

The 4-month sleep regression

All new parents have heard about the dreaded 4-month sleep regression even if they’re not quite sure what it is, why it happens or how to get through it. But what they have heard is how brutal it can feel!

You’re just getting into the swing of your baby’s little routines, their sleep patterns (or lack of), just staring to feel like you’re no longer winging it… then out of nowhere the 4-month regression hits! 

Naps get shorter, nights become even more disrupted, and your once-settled baby suddenly needs a lot more help with falling (and staying) asleep. It can feel chaotic and exhausting but knowing what’s behind this sudden shift can make it much easier to navigate.

What is the 4-month sleep regression and why does it happen?

Once you understand why the 4-month sleep regression happens, it often feels far less overwhelming. It will help you to respond with calm reassurance instead of panic and this can help you feel more confident and in control as you work through this stage.

The 4-month regression is a developmentally normal biological shift that all babies will go through usually between 3½ to 4½ months old. It’s definitely not something you’re doing wrong; it’s a sign your baby is growing and developing exactly as they should.

Here’s what’s happening:

• Your baby’s brain and body are making rapid growth changes.
• Their sleep is maturing, they’re moving from newborn-style sleep stages to adult-like sleep cycles, which include light and deep phases.
• This new sleep structure means they’re more likely to wake between cycles and need help falling back asleep.

Some babies sail through this transition with minimal disruption, while others find it more difficult. Either way, it’s temporary and manageable.

Common signs of the 4-month sleep regression

If you’re wondering whether your baby is going through the 4-month regression, here are some common signs to look out for:

• More frequent night waking
• Struggling to settle to sleep without your help
• Short 45–60 minute naps
• Changes in mood, clinginess, or fussiness during the day

How to support your baby’s sleep through the regression

While you can’t stop the regression from happening, you can gently support your baby through it, starting to lay the foundations for better, more settled sleep moving forward.

Here are some practical, parent-friendly tips:

• Practice self-settling (gently) – Start offering opportunities for your baby to fall asleep on their own by putting them down tired but not fully asleep whenever possible. This gives them a chance to practice self-settling, even if they still need some help from you at times.
• Create a consistent wind-down routine – A short, predictable routine before naps and bedtime (cuddle, lullaby and a sleepy phrase) helps your baby recognise that sleep is coming and makes the transition to sleep smoother.
• Try not to add in new sleep habits – It’s tempting to start rocking, feeding, or bouncing to sleep if your baby is struggling during the regression. But if they didn’t need it before, try to avoid introducing it now. Stick to what worked previously, while offering plenty of reassurance and comfort.
• Follow a flexible nap schedule – Focus on a responsive routine that follows your own baby’s sleep cues and wake windows instead of a rigid clock-based schedule. This helps avoid overtiredness, which often makes falling asleep even harder for babies.
• Stay calm and consistent – This phase can be exhausting, but it will pass. Keep offering reassurance and try to stick to your usual sleep expectations as much as possible. Babies feel secure with consistency and so do parents.

The 4-month sleep regression is a tough chapter, but it’s also a sign of positive development. With a bit of knowledge and a few gentle adjustments, you can support your baby through it with confidence.

If you’re feeling stuck or overwhelmed, know that you’re not alone and support is always available. Sometimes even small changes can make a big difference.