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4 Month Sleep Regression Explained

How To Survive the Four-Month Sleep Regression Explained          

The four-month sleep regression can be a tricky milestone for any new parent. 

It often starts at the peak of your sleep deprivation limit and can test your patience and resilience!

You probably feel like you have just got into a great rhythm with your little one’s sleep and are finally enjoying some more solid stretches of sleep at night. Then BAM along comes the four-month sleep regression, and you feel like sleep has gone out of the window again. 

Trust me, I’ve been there, and I know it can feel like a real blow. 

Firstly, as a certified sleep coach, I’m here to reassure you that this regression is a normal developmental change in your baby’s sleep. It’s a positive sign that your baby is growing and developing well!

Secondly, and most importantly, I want you to remember that it is temporary and will pass.

Check out the following guide to learn more about what sleep regression actually is.

The 4 Month Sleep Regression Explained

4 Month Sleep Regression Explained

The four-month sleep regression most commonly occurs between 3 and 4 months (12 – 16 weeks) but can even happen as late as five months (20 weeks) in some babies. Unfortunately, there is no set week for this regression to start and end. Depending on your baby and temperament, it can last anywhere from a few days to a couple of weeks. 

The four-month sleep regression is a biological change in your baby’s sleep. Unlike other sleep regressions based on developmental learnings and changes, the four-month sleep regression fundamentally changes your baby’s sleep as it matures and becomes more adult-like. 

Previously your baby will only have taken active (light) sleep during each sleep cycle. They can now go through two phases, taking both active (light) and quiet (deep) sleep in each sleep cycle. 

When the four-month sleep regression starts, your baby often gets ‘stuck’ between quiet and active sleep, which is why you may see more frequent night wakings and shorter naps. It’s also why you may need to help your baby back to sleep more than usual. 

Remember, it is a positive developmental milestone in your little one’s sleep. I like to think of it as a sleep transformation rather than a sleep regression!

How to know if your baby is experiencing the four-month sleep regression

Here are the key signs I always look out for when it comes to the four-month sleep regression:

  • Your baby is suddenly refusing or fighting their naps, especially the naps later in the day. Getting them down for a nap may have become more challenging, or it’s taking you much longer than usual to get them settled.
  • Naps are short, only lasting 20-40 mins, when previously they were napping for much more extended periods.
  • Bedtime is becoming more of a battle, and your baby is more difficult to get down for the night.
  • Your little one is suddenly more reliant on outside sources to fall asleep. For example – rocking or needing movement, a pacifier and feeding to sleep.
  • Your baby is hungrier than usual. This regression often ties in nicely with a growth spurt. If you are breastfeeding, you might feel like your baby is constantly feeding on you right now. If you’re bottle feeding, your baby is likely quickly draining his bottles during this period and looking for extra feeds. 
  • Your previously calm and content baby is suddenly grumpy or fussy during the day.
  • You are experiencing more frequent night wakings and giving extra feeds during the night.
  • You are finding it harder to settle your baby in the middle of the night, and the methods you previously used aren’t as effective. 

My top tips for navigating the four-month sleep regression

Keep your baby’s wake windows nice and short:

baby's wake windows

An average four-month wake window is 1.5-2.5 hours, with the shortest awake period being first thing in the morning, before their first nap. This will help avoid overtiredness building throughout the day. If your baby is overtired, it can make bedtime harder and night wakings more frequent.  

The easiest way to ensure your baby’s wake windows are correct is to watch them closely for their sleepy cues:

These can be subtle, so be curious about your baby and study them. Some early sleepy signals to look out for are; losing interest in toys/people, a glazed expression, red-rimmed eyes, and looking pale. When you see these early sleepy signs, this is your baby’s signal that it’s time to put them down for a nap.

Focus on a predictable pre-nap and bedtime routine.

Babies like to know what’s coming next and thrive from a predictable routine. During a time when so much is changing in their small world, a consistent pre-sleep routine can help keep them calm. An example pre-nap routine might look something like this:

Feed your baby
  • Shut the curtains or blinds: A dark room is not essential for day naps, but lowering the light level in the room can help your baby get ready for sleep & help them wind down. 
  • Pop their sleeping bag on: Take off any bulky layers & pop your little one into their sleeping bag
  • Feed your baby: Making sure your baby is taking a nice, full feed before their sleep will help lengthen that nap as much as possible and eliminates any unnecessary waking from hunger
  • Connect & cuddle with your baby: Reading one short story or singing a lullaby whilst having a cuddle is a lovely way to connect before your little one’s sleep
  • Put your white noise on: Low, consistent white noise for naps helps drown out any background sounds that might disturb your little one
  • Use a consistent sleepy phrase: Having a phrase you say every time you put your baby to sleep can be a really helpful sleep association. I use ‘It’s sleepy time now, Teddy’ for my son.
  • Put your baby down for their nap: Lay baby down in their cot whilst repeating your sleepy phrase

White noise and a dark room can help to settle a baby who is worked up:

If your baby is frustrated or fussy, try taking them somewhere nice and quiet in the house to calm them. Try drawing the curtains, putting your white noise on low and using your voice to comfort your baby; this often helps them settle down. It’s also a perfect moment to take a long, deep breath! 

Practice any new skills during the day, away from sleep:

If your little one is trying to roll or sit independently, keep practising these skills during the day to make them less attractive at night or at nap time! Quite often, the 4-month sleep regression coincides with some key developmental milestones, which can also affect your baby’s sleep.

It might be necessary to make temporary changes to your methods and schedule to survive this tricky phase:

For example, if your baby is sleeping best on the go, then prioritise naps in the buggy, sling or car for a week or two. Or if your baby is sleeping best from 7 pm-10 pm, but then the rest of the night is chaos, consider moving your bedtime forward and get your rest in when you can. Don’t be afraid to adjust your routines; you can always change them back once this developmental leap has passed.

Sleep training and the four-month sleep regression

Sleep training

I advise waiting until you’ve passed through the worst of the regression before attempting any sleep training. It is challenging to remain consistent when navigating a sleep regression, and you need consistency, above all else, when tackling sleep training. 

Once you are through the regression, it’s a great time to work on your baby’s sleep! Now you can work on independent settling methods and get into a more consistent routine.  Your baby’s sleep has developed and matured, so, in theory, you should be able to start seeing longer stretches of sleep at night now. 

If you are still struggling with sleep and feel that it’s not because of the regression anymore, this can be a great time to work with a sleep coach or consultant who can guide you whilst working with your parenting style and specific family goals.

And lastly, if you take anything away from this article, let it be this:

Be kind to yourself, and remind yourself that this will pass. This phase does not last forever, and you will be back on track soon. 

I found it helpful to have a mantra I said over and over to myself in tough, sleep-deprived moments with my son – ‘I am a good Mum, my baby is safe and loved, they WILL sleep again’. 

Yours may look a little different to this, but having a positive mantra to return to can make a difference in those tired, lonely moments.


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

Answer: Yes, every baby’s sleep cycle will biologically change at some point between 3 and 5 months. However, not every baby experiences a dramatic change in their sleep patterns, and some parents do not notice any change in their little one’s overall sleep. You might be one of the lucky ones!

Question: Can I prevent the four-month sleep regression?

Answer: Unfortunately not; there is no real way to avoid the four-month sleep regression as it is a developmental stage all babies go through. However, you can put strategies in place to make the sleep regression go as smoothly as possible. Creating an ideal sleep environment for your baby by using healthy sleep associations can help. For example, using consistent white noise, keeping the sleep space dark, using a familiar sleepy phrase around sleep and using a predictable routine pre-nap and bedtime.

Question: How do I know if it’s the four-month sleep regression or a bad week?

Answer: If you are in the four-month sleep regression, you will likely be experiencing many of the listed key signs above; fighting naps, more frequent night wakings, usual settling methods not working, a fussy baby and a baby who is extra hungry. These signs will also last for five days or more. Often if sleep goes off track for teething, illness or a growth spurt, for example, it is only for 2-3 days at a time. That said, growth spurts and regressions tend to go hand in hand, so you may be experiencing both at once!

Question: My baby seems extra clingy; is that normal?

Answer: Yes! It is usual for your baby to experience changes in their mood and temperament during the four-month sleep regression. Most commonly, you might be experiencing extra fussiness or tears during this time. Remind yourself that a lot is changing in your little one’s world right now, and often they are looking for extra reassurance and connection from their parents.

The Four-Month Sleep Regression: Key Takeaways

The Four-Month Sleep Regression: Key Takeaways

If you are short on time, like most sleep-deprived parents are, here are my key takeaways for the four-month sleep regression:

  • The four-month sleep regression can occur between 3 and 5 months; there is no set time for it to start or end. 
  • It is a biological change in your baby’s sleep cycle as they mature and their sleep becomes more adult-like. 
  • It is a temporary phase and will pass. Stay calm!
  • You should wait to attempt sleep training with your baby until after the regression has passed. 

Don’t hesitate to contact your pediatrician if you have any concerns about your baby’s development or weight. 

For more practical help and advice on your baby’s sleep, please visit Upside Dad.