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The 4 Month Sleep Regression

by | Aug 15, 2023

Has your infant transitioned from being a relatively good sleeper, capable of self-soothing, seamlessly transitioning between sleep cycles, and easily taking daytime naps, only to experience the complete opposite?

Have they reached the age of 4 months, and suddenly everything has turned upside down? Are they waking up frequently at night, struggling with unsettled nap times, and resisting falling asleep? If so, please know that you are not alone.
However, what exactly causes such a drastic change in a baby’s sleep patterns at the 4-month mark?

I’m Tori founder of This Parent Can, infant sleep specialist, maternity practitioner, and Mummy to 4 little people.

Here is everything you need to know about the 4 month sleep regression…..

What is a sleep cycle?

Sleep cycles are the different stages your baby will go through when they are asleep. Babies sleep cycles at this age tend to be between 30 to 50 mins long during the day and around 2 hours at night. There are 4 stages:

  • Falling asleep – this could be popping them in their sleep space, and they drift off independently (often known as self – settling), or being fed to sleep, rocked to sleep, held to sleep etc.
  • Active sleep/REM – this is when your little one may be shuffling around, eyes may flicker, they may even make a few noises and you may question if they are really asleep.
  • Deep sleep – at this stage their breathing will steady, they will be very still and even if the dog starts barking or your toddler starts playing right by them, they will not stir.
  • Transition phase – this is when your baby will wake through their sleep cycle, they may have a little cry, babble, move around a bit and then (ideally) get themselves back to sleep – this is known as linking sleep cycles. If they can’t fall asleep independently then this is when they will be looking for whatever it is they need to get themselves back to sleep.

What are the signs for the 4-month sleep regression?

For some babies it will be really obvious when the regression hits, for others it will be more subtle, and parents may not notice at all. The most common signs are:

  • Shorter naps – they usually start doing only one sleep cycle so around 30 to 50 mins.
  • Fighting sleep – they may start to find it harder to settle to sleep and the way you would usually settle them no longer has the desired effect.
  • Frequent night waking’s – It is totally normal for 4-month-olds to still need a night feed, but if you have gone from one or two night waking’s for a feed to them waking every 2 hours then it can be a sign they have hit the regression.

How Can We Help?

There are 4 main things we can look at when helping our little one through the 4-month sleep regression:


Look at the environment that your baby is being put to sleep in. Our aim is for it to be dark as this will help their body produce the sleep hormone melatonin, cool it is recommended that our little one’s sleep in temperatures of around 19 degrees C, using consistent white noise, this can be helpful for blocking out any background noise – make sure it’s on for the whole nap/night.

Correct awake windows

Awake windows are the length of time your baby can be awake for between naps/bedtime, I have a free download on this – Understanding Awake Windows.

They can truly be your best friend when it comes to infant sleep!
Having the correct, age-appropriate awake window ensures your little one is going to sleep tired, and you are avoiding them being under or overtired. This usually helps them fall asleep independently, sleep for a good chunk of time, and encourages them to link their sleep cycles. At 4 months the average awake window is between 1hr 45 min to 2 hours.

Day time naps

Day time naps play a massive part in your baby settling well and sleeping well at night by preventing them from becoming overtired and overstimulated. It may be time to look at gentle nap routines for your little one.

Sleep associations

We all wake up during our sleep cycles when we transition between deep sleep into light sleep, but as adults we tend not to remember it. Babies, on the other hand, may wake up fully. If your little one is used to being, for example, rocked or fed to sleep, then they are going to need the same thing done to get them back to sleep every time they wake up. There is ABSOLUTELY nothing wrong with any of these if it is working for you, if it isn’t and you want to encourage your baby to fall asleep without needing something from you then it may be time to work on independent sleep.

Sleep coaching

Some babies need a little more help to get them back to being solid sleepers. This is where you can use a gentle, consistent sleep coaching method that feels right for you and your baby.

Remember, you matter too, and if you have been hit hard by this change in your babies sleep pattern then make sure you ask for help. Lower your expectations on what you will achieve in a day when you have had 2 hours sleep, listen to your mind, and body, and get some rest whenever you can.

Remember to eat, stay hydrated, get some fresh air, and ask for help!

Tori Drew

If you feel you need guidance with the 4-month sleep regression, or any other early years sleep then please get in touch – Have a look at my 1:1 support packages and phone calls, Age Appropriate Downloadable Routines and my Instagram – @thisparentcan.