surviving the 4 month sleep regression

What’s Going On with My Baby’s Sleep?

You may have had a newborn who slept like a dream… but now that your baby is around 4 months old, things have changed. Suddenly, they’re waking more often at night and only napping for short stretches during the day. You’re exhausted and probably wondering — what happened?

Welcome to the world of the 4-month sleep regression — one of the biggest changes in your baby’s sleep journey. But don’t panic — understanding what’s going on and knowing how to respond can make all the difference.

What is a sleep regression?

A sleep regression is a period where a baby who was sleeping well suddenly starts waking more at night, skipping naps, or having trouble settling to sleep. It’s a totally normal and natural phase — but understandably tough on tired parents.

Your baby will go through several regressions in their first two years, but the 4-month regression is the most significant.

So, what causes the 4-month sleep regression?

At around 4 months old, your baby’s sleep patterns start to mature. Instead of drifting in and out of sleep without fully waking (like they did as newborns), their sleep cycles begin to resemble ours as adults — alternating between deep and light sleep.

Here's what shifts:

• Daytime sleep cycles become about 35–45 minutes long.

• Nighttime sleep cycles shorten to around 2 hours.

• Your baby now fully wakes at the end of each cycle instead of smoothly transitioning between them.

This shift often leads to frequent night wakings and catnaps. But here’s the key: this isn’t a regression in development — it’s a progression. It’s a big step forward in your baby’s neurological growth!

Why sleep associations matter now

Because sleep is becoming a more active process, how your baby falls asleep matters more than ever. If they rely on rocking, feeding, or patting to doze off, they’ll need that same help every time they wake between cycles — which can be every 2 hours at night and every 45 minutes during naps.

So if you’re doing the math… yes, that’s a lot of wake-ups!

Note: Not all babies hit this phase right at 4 months. If your 3.5-month-old suddenly starts waking every 2 hours, chances are they’ve reached this milestone early.

How long does the 4-month regression last?

Here’s the tough truth: this isn’t just a phase your baby will grow out of — it’s a permanent change in how they sleep. The solution? Helping them learn to fall asleep on their own.

Self-settling means your baby can fall asleep on their own, without needing your help every time. And yes, they can learn how — if their day is set up well with appropriate awake times, naps, and a predictable routine.

From this age forward, the way your baby falls asleep becomes the way they expect to fall asleep every time. If that same sleep association isn’t there later, they’ll struggle to return to sleep on their own.

How can I help my baby learn to self-settle?

Think of self-settling as a skill, like learning to read — it takes time, practice, and the right environment. Here are some essentials:

• Babies under 3 months don’t consciously self-settle yet, but you can encourage good habits and set them up for success.

• Expect some protest, especially from older babies used to being actively settled.

• Overtired or undertired babies will find self-settling harder.

• Be consistent — mixing things up sends confusing signals.

• Create a sleep-friendly environment: think dark room, white noise,  swaddles  (if under 5 months and not rolling), or a sleep sack.

• Make sure they’re fed and burped before sleep — a hungry baby won’t settle.

Will this ruin any sleep progress we have made?

Not at all! If you’ve started creating routines or introduced self-settling already, great — that work will pay off.

Having a consistent structure helps you spot sleep regressions more easily because you’ll recognise sudden changes in your baby’s usual sleep behaviour. And while regressions can make things tricky, staying consistent with naps and awake windows really helps smooth things out.

Surviving the 4-month sleep regression

This period is tough, but there are ways to make it easier:

• Identify what’s causing the wake-ups — often, it’s a strong sleep association such as feeding to sleep, patting to sleep etc (remember, this is only an issue it is an issue for you as the parent!).

• Start a gentle plan to reduce those associations and support self-settling.

• Give your baby a chance to settle before jumping in.

• Keep their sleep space dark and distraction-free, with continuous white noise.

• Stick to age-appropriate nap and awake times — routines are your best friend.

• Begin a calming bedtime routine — it helps signal that sleep is coming.

• Gradually reduce how much you help your baby to sleep — aim for one nap a day in their bed.

Remember: waking for one extra feed isn’t the same as waking every two hours for small top-ups. If they’re feeding every time they stir, chances are they’re using feeding as a way to get back to sleep — not because they’re actually hungry.

The 4-month sleep regression is a major milestone — but also an amazing opportunity to build strong, healthy sleep habits. With patience, consistency, and the right support, your baby will come through it sleeping better than ever.