The 4 month sleep regression: Why has my baby’s sleep changed?
What’s really happening at 4 months? The science bit.
At around 3 - 4 months old, your baby’s sleep starts to mature. Their sleep cycles of light and deep sleep become more defined, much more like an adult sleep pattern.
A baby's daytime sleep cycle is often around 30 - 45 minutes, with sleep cycles generally becoming longer overnight.
The stores of melatonin (our sleep hormone) that your baby was born with are also starting to deplete, meaning they become more alert and aware of their surroundings.
And there can be plenty of other things going on at this age too. Vaccinations, increased physical development and babies becoming hungrier can all have an impact on sleep.
There is a lot happening!
But I like to think of the 4 month sleep regression as a sleep progression, not a regression.
Your baby’s sleep isn't going backwards. Their sleep is developing and becoming more mature. In fact, the 4 month sleep regression is the one commonly discussed sleep regression that has a clear biological and developmental basis.
Signs of the 4 month sleep regression. Now every baby is different, but you might notice:
Shorter daytime naps or lots of catnapping, often around 30 - 40 minutes
More frequent night wakes
Difficulty settling to sleep
Early morning waking
A more overtired or grumpy baby
Your baby suddenly needing more help to fall asleep
You may feel like your baby was sleeping beautifully and has suddenly changed overnight!
But this doesn't mean anything has gone wrong.
As your baby becomes more aware of the world around them, they also become more aware of how they fell asleep.
For example, if your baby is rocked, fed or cuddled to sleep, they may look for that same support when they naturally wake between sleep cycles.
So, if your baby falls asleep being cuddled and is then placed in their cot, they may wake 30-40 minutes later when they reach the end of a sleep cycle and look for that same support to get back to sleep.
This is what we call a sleep association. Your baby has simply learned to associate falling asleep - and getting back to sleep - with support from Mum or Dad.
So, how can you improve sleep at 4 months?
1. Look at awake windows
An overtired baby can find it much harder to settle and link sleep cycles.
At around four months, awake windows are often around 1 hour 45 minutes, stretching towards 2 hours later in the day.
If your baby is consistently struggling with naps, it can be worth gently tweaking their awake time by around 10 minutes either way and seeing whether this helps.
2. Focus on feeding
Around this age, babies can become incredibly distracted during feeds. Suddenly, the world is much more interesting and some babies start taking shorter or less focused feeds during the day.
If distractions are becoming an issue, try feeding somewhere quiet and calm. Getting the right about of feeds and calories in during the daytime can really help night-time sleep.
3. Optimise their sleep environment
Your baby is becoming much more aware of their surroundings, so creating a good sleep environment can really help.
A good blackout blind can help keep the room dark and reduce distractions. Darkness also supports the body's natural production of melatonin. And don't worry about your baby being afraid of the dark - they don't need a nightlight.
White noise can also provide a consistent background sound and help mask household noises that could otherwise disturb your baby as they move into lighter sleep.
4. Encourage self-settling
Now, this one is key.
Have a think about how your baby falls asleep at the start of their nap or at bedtime. If they are being fed, rocked or cuddled to sleep, when your baby naturally wakes between sleep cycles, they may look for whatever helped them fall asleep in the first place.
This doesn’t mean you need to suddenly stop all of the things you currently do to help your baby sleep. But you can gradually start reducing those sleep associations and giving your baby more opportunities to practise falling asleep independently.
There are different ways to work on self-settling. Some babies respond well to reassurance in their cot through gentle touch, patting and shushing, while others do better when given a little more space to try to settle themselves, with you returning at regular intervals to offer reassurance.
If you’re starting to work on self-settling, try practising it at bedtime, when melatonin levels (that’s the sleepy hormone) are naturally higher or with the first nap of the day.
One of the simplest things you can try is to watch and wait when your baby wakes. Babies can be surprisingly noisy when they move between sleep cycles. They may wriggle, grumble, babble or even have a little cry before settling back to sleep.
Give your baby a minute or two to see if they can resettle themselves. Sometimes they might surprise you! And if they don't settle, you can then go in and offer the reassurance they need.
The important thing is to give them the opportunity to practise this new skill. Just like any new skill, it takes time, patience and consistency. You will get there.