The 4-month sleep regression is actually a permanent sleep development. In this article, we look at what’s happening in your baby’s brain, why sleep suddenly changes, and how parents can respond gently during this phase.

Somewhere between 3 and 6 months, many babies go through the 4-month sleep regression. It’s a phase where they suddenly start waking more at night.

After a period of longer sleep stretches, your little one might now wake more frequently. While it can feel like a step backwards, this regression is actually a sign that your baby’s sleep is maturing.

Sleep advantages that are happening now

Mature sleep cycles and deeper sleep.

Making their own sleep hormones.

They are bigger and may need less milk at night.

What’s a sleep cycle and why is it important?

A sleep cycle is a period of sleep that includes some light sleep [REM] and deep sleep [NREM.] After each sleep cycle it’s normal to wake up slightly. An adult sleep cycle lasts about 90 minutes and a baby’s lasts about an hour.

At around 4 months, babies come out of newborn sleep and into a mature pattern of sleep cycles. They wake naturally, every hour. 

 

Here’s what a baby’s sleep cycle looks like

Sleep hormones

From about 3 months, your baby produces their own sleep hormone – melatonin. Before this, they got melatonin from the placenta and from breast milk. Also, being very close to you, they ‘shared’ your circadian rhythm until they developed their own.

Getting bigger

Young babies need to feed regularly, including during the night. They are growing very rapidly and their little tummies can’t hold enough milk to sustain them for long.

By 4 months, their rapid growth settles into a slower and steadier weight gain. Many babies of 4 months have the body weight to sleep for stretches of 5 hours or more at night without getting hungry. 

So given that all this positive stuff is going on, it can be frustrating when babies start to go backwards with their sleeping!

Why does the 4 month sleep regression happen? 

Between 3 and 6 months, babies become more conscious of what is going on. They start to figure things out and make learning connections. These connections, made as they fall asleep, can develop into expectations and preferences around their night sleeping and napping. In other words – habits are formed.

So as an example – if they are fed or cuddled to sleep at the start of the night, they may need or expect those same “sleep triggers” when they wake up naturally after a sleep cycle. All of this happens at the same time as their sleep patterns change!

Of course, it is fine to cuddle or feed your baby to sleep if that’s what feels right for you or if that’s what they need. Be aware though that if at this age, they start to wake for feeds and cuddles more than they used to; there is a good chance that they are doing out it of habit rather than need.

This can be disruptive to their sleep and yours also. 

How to protect their sleep during the 4 month sleep regression

♥ A good bedtime routine really comes into its own now. It’s just a repeated series of steps leading up to bedtime that baby will recognise as sleep cues. See my great bedtime routine for ideas of how to build your own!

♥ Independent settling. It’s good to help them fall asleep in the cot aware of where they are. A lovely way of doing this is to give the last feed with the light on and follow it with a simple book. Then turn the lights off and put them down into the cot awake. Soothe them there if they don’t like to be left, or leave them to self-settle if they’re ok with that. 

The more independently they fall asleep at the start of sleep, the more likely they are to be able to join their sleep cycles by themselves. 

♥ Daylight exposure and darkness at night will help set your baby’s circadian clock so they sleep better.

♥ Enough daytime sleep. During the 4 month sleep regression, naps as well as night time sleep can take a hit. It’s normal during this period for babies to take frequent shorter naps instead of fewer, longer ones. Give them the opportunity and the space to have their little naps and try not to get worried that the naps are short. With maturity the naps will extend. You might find that your baby sleeps better during contact naps, and it’s fine to do this if you want to or choose to.

♥ A comfortable and consistent sleep space. As sleep now happens in cycles; it is normal to wake a few times in their sleep. When your baby wakes up, they will need to have everything around them, the same as it was when they fell asleep. This means that they will be happier if they fall asleep in the place where they are going to sleep all night. It also means that things like lighting and sound levels are the same all night.

The exact moment to put your baby down is……

……when they have had the right wake window and are tired but not over tired. The wake window will depend on their age, their individuality and their daytime activities [they’re always exhausted after swimming for example!] 

Parents often make the mistake of putting their baby into the cot ‘drowsy but awake.’ If a baby gets too drowsy, they may break the build up of sleep pressure they need to be able to fall asleep. This can mean they struggle to drift off, even when they’re very tired.

 

When they wake up during the night or during a nap

If your baby wakes up, you can leave them for a few minutes if they’re not unwell, hungry or upset. When they call or cry for you, try soothing them in the cot for a while rather than automatically picking them up or feeding them. They might just resettle and drift back off but if they continue to cry, respond with whatever feeding or cuddling they need. 

If they start feeding more at night than during the day [Reverse cycling]

Watch out that they don’t feed so much at night that they have no appetite for feeds during the day!

This is such a common situation and is called reverse cycling. If your baby feeds a lot during the night you might find that they feed distractedly during the day. You may be constantly trying to tempt them or persuade them to feed! And then as soon as it is dark and quiet, they will take good sustained feeds. This can soon become an established feeding pattern and it can be difficult to break away from. How can you possibly stop the night feeds if these are the only ones your baby takes?

If you wait for your baby’s daytime appetite to improve before reducing night feeds, you could be waiting for a very long time!

The best way to approach this is to gradually cut down on the night feeds and then you’ll find that the daytime feeds will gradually increase.

Will this regression pass by itself?

For some babies, this is a phase and it will pass. For others, the habits which form now can stick, and their wakeful nights become the norm.

If you’re struggling, you’ll find more help to establish good sleep habits in my SettledSleep Plan and also in my book, Gentle Sleep Solutions.

Does every baby go through the four-month sleep regression?

No! Many babies naturally sleep for longer periods as they get bigger and older. This is especially true of babies who can self settle,  or have a naturally very calm disposition.

In my experience, babies who do go through this regression are usually very alert and engaged!

Take away

• The 4 month sleep regression is a natural phase that many babies go through.

 

• A consistent bedtime routine will help with their sleep, as will avoiding over tiredness.

 

• Helping them to fall asleep independently at bedtime encourages them to join their nighttime sleep cycles.

 

• Watch out that bedtime and night feeding doesn’t become a sleep association – meaning they start feeding more at night than during day.

Further Help

If you’re struggling with the four-month or any other sleep regression, I am here to help you.

My books

My bestselling books give you the tools to help your baby and yourself get a good night’s sleep. They are full of expert, practical advice and case studies. Each book teaches you to create your baby or child’s personal sleep plan and is written in a clear and accessible style.

They are available in all formats from Amazon and other booksellers.

 

Private Consultations

If you choose to book a one-to-one consultation with me, you will receive my individual advice. You will be in very safe, experienced hands and I treat every parent and child with kindness.

As a qualified nurse, mental health nurse and health visitor, I can help families with medical and developmental issues.

My success rate is outstanding, with over 15,000 face-to-face sleep consultations with families from all over the world.

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