The four month sleep progression

This is possibly the most prominent and discussed sleep regression and while it’s common for families to experience some sleep disturbances, not all do. 

With this, and any other coined sleep regression, it can be really unhelpful to worry and catastrophise something that hasn’t happened yet.

Because seriously, for some, you wouldn’t even know anything had happened. 

So let’s break this down.

Literally, what is happening during the four month progression?

This is the only coined sleep regression/progression that has anything to do with actual sleep.

Firstly, it’s important to note that while it is commonly coined the 4 month sleep regression, this change can actually occur anytime between 3 and 6 months. 

The predominant cause is the maturation of the baby’s sleep cycle. So they are literally changing the architecture of their sleep, which understandably could be a little jarring for your small one. 

REM sleep, also known as dreaming sleep, is paramount for brain maturation and the formation and processing or memories. This is probably why newborns spend 80% of their sleep in REM and the rest of the time in NREM3/4, which is the deep, quiet sleep. 

What we don’t see in the newborn months are NREM 1 + 2. These are the lighter stages of quiet sleep and during this time one is easily roused. These states create a nice transition from being awake to falling deeply asleep.

So during this time your little one’s sleep architecture is biologically changing.

A newborn sleep cycle looks a bit like this…

REM – NREM3/4 – REM – NREM3/4 etc

Then as it develops it forms this shape…

NREM1 – NREM2 – NREM3/4 – NREM2 – NREM1 – REM – NREM1 etc 

As your little one’s sleep cycle matures they are introduced to a more complex sleep architecture.

The four month sleep progression

As your little one’s sleep cycle matures they are introduced to a more complex sleep architecture. 

As mentioned above, many don’t notice any negative side effects but for those who do they can be:

  • More frequent night wakings
  • Startling awake soon after falling asleep as they transition into a deeper sleep
  • Difficulty with naps either being shorter or missed all together
  • Harder to settle at bedtime
  • All of these can lead to fussier and crankier babies

Some people feel like this regression lasts forever.

It doesn’t.

It’s important to note that there are other things going on that potentially need addressing to smooth out any ongoing issues. This is alongside having an understanding that development is always progressing and this can carry some ups and downs in infant sleep.

  • As babies become more aware and alert they, in turn, become more easily distracted. This can disrupt daytime feeds and lead to them wanting to feed more at nighttime. You could try wearing a nursing necklace while feeding to keep them focused on the right area. Alternatively, feeding right before a nap or as soon as they wake up, while they are calm and in a quiet place can help optimise those day feeds.
  • Over this time your baby’s sleep need will decrease by up to two hours,  and they may drop a nap in the latter half of this period. You may find you are still trying to achieve the same amount of day sleep as before and finding this a struggle or it’s affecting their nights. This can bring its own challenges with finding the right balance for you and your little one. A little trial and error with timings and reading your baby’s sleep cues can work wonders.

This time can be really hard for some. I feel you. You may have just started to feel like you are really getting into your groove and getting some consolidated night-time hours sleep and then suddenly it’s all moving backwards. But…

It will pass. I promise. 

It is developmentally normal and your little one just needs a little practice at transitioning through their new cycles. 

Some tips – 

  • Look after yourself
  • Let go of less important chores and tasks
  • Rest when you can
  • Go to bed earlier
  • Try not to freak out about it
  • Try stretching their awake time very slightly
  • Optimise daytime feeds
  • Try white noise and a calmer nap environment if doing cot/bed naps. They are more alert now and going through lighter sleep cycles so might settle better with some dim lights and calm. Their circadian rhythm is normally setting in to place by around now so some dim light for naps won’t play havoc like it can in the first few months. This definitely isn’t paramount, but for some particularly distracted little ones it can be beneficial
  • The closeness and motion of carrier and contact naps are also really helpful for many


And remember – 

  • You aren’t doing anything wrong
  • Your little one isn’t broken
  • They don’t need to learn to self settle to get though it
  • You don’t need to stop feeding to sleep
  • You don’t need to stop supporting to sleep
  • You haven’t spoilt them
  • They will sleep better
  • You will sleep better again

I promise.

If you are worried about anything and are struggling with you little one’s sleep then hop over to my website ( www.secondstarsleep.com ) to explore my support options.

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