Your baby was sleeping in lovely long stretches. Then, somewhere around four months, it all fell apart: waking every couple of hours, naps of 30 minutes, and a baby who won't settle the way they used to. If that sounds familiar, you're probably meeting the famous 4-month sleep regression.
The good news: nothing has gone wrong. The slightly harder news: it's a real change, not just a phase you can wait out.
What is the 4-month sleep regression?
In the first few months, newborn sleep is quite simple. Babies drop into deep sleep easily and can often sleep through noise, cuddles and car journeys.
Somewhere between three and five months, your baby's sleep matures. It starts to move through cycles of lighter and deeper sleep, much more like yours does. During the day, a nap sleep cycle lasts around 30 to 45 minutes. Overnight, cycles are around two hours. At the end of each cycle your baby comes up into very light sleep, or briefly wakes.
That's why some people call it a "progression" rather than a regression. It's your baby's brain developing exactly as it should. But more light sleep means more moments where your baby notices where they are, and whether things are the same as when they fell asleep.
Signs of the 4-month sleep regression
- Waking more often at night, sometimes every one to two hours
- Short naps of 30 to 45 minutes, roughly one sleep cycle
- Harder to settle at bedtime, or waking soon after going down
- More fussing and wanting to be held
- Rolling, grabbing and babbling practice, sometimes at 2am
Not every baby shows every sign, and some sail through with barely a wobble.
How long does it last?
The most unsettled patch commonly lasts a few weeks. But because the change in sleep is permanent, some babies keep waking frequently long after that, especially if they rely on something that disappears once they're asleep to get back to sleep, like being fed, rocked or held.
That isn't a bad habit or something you've done wrong. Feeding and cuddling a baby to sleep is completely normal. It only becomes a problem if it's no longer working for your family.
What helps
There's no magic fix for a developmental change, but a few things make this stage easier:
- Keep days predictable. A similar rhythm each day, with naps at roughly the same times, helps your baby's body clock settle.
- Make the room sleepy. Dark for naps and nights, with a comfortable temperature.
- Sleep train. Teach your baby the skills they need to be able to sleep independently.
- Give your baby floor time. Lots of practice rolling and moving during the day can mean less practising at night.
- Look after yourself. Take turns with a partner if you can, accept help, and go to bed early when you get the chance.
Keep following safe sleep guidance throughout: always on their back, in a clear cot. Once your baby starts showing signs of rolling, it's time to stop swaddling.
When to speak to a professional
Sleep regressions don't cause fever, feeding refusal, breathing difficulties or a baby who seems unwell. If you notice any of these, or you're worried at all, speak to your GP, health visitor or paediatrician. Trust your instincts.
But you don't have to do it alone
If the regression has settled into a new normal of frequent waking and short naps, and you're all exhausted, you don't have to just wait it out. This is the stage where a plan built around your baby can make a real difference.
I work with babies from four months, and every plan is based on your baby's temperament, feeds and routine. I don't use "cry it out" and will always support your breastfeeding journey. Book a free 15-minute call and we can talk about what's going on.