4-Month Sleep Regression

Learn some tips to navigate the 4-month sleep regression!

If you’re at about the 4-month mark and feel hopeless the second the clock strikes bedtime, I see you. The 4-month sleep regression is to be expected- but it can be brutal. Just when you thought you were through with the newborn sleepless phase, it can feel like it comes out of nowhere. Sleep regressions are a normal milestone around 4 months, 6 months, 12 months, 18 months, 2 years, and 3 years old. Today, I’m talking all about the 4-month sleep regression to help answer some of the questions you may have! 

4-Month Sleep Regression

You may notice that your little one isn’t sleeping as well as they were before- this may mean that they’re in a sleep regression. The 4-month sleep regression happens around the same time that you can begin sleep training. This is when babies are developmentally ready to start learning independent sleep skills. Their sleep patterns may be starting to appear with longer waking times and more regular nap times (and maybe, if you’re lucky, even sleeping through the night). This is exciting because sleep training is SUCH a game changer for the whole family. A happy, well-rested baby means happy, well-rested parents! 

At the 4-month mark, there are many developmental milestones in the works that your baby is growing through. They’re learning so much about the world around them, developing physically and mentally, they may be teething, and going through so many other changes right before your very eyes! 

This is super exciting to watch as parents- but then you get hit with the 4-month sleep regression. All of these developmental changes can become overwhelming for your baby, and you may notice an increase in night waking, fussiness, or disrupted nap schedules. The 4-month sleep regression typically lasts for a few weeks and isn’t cause for concern. Your baby will adjust in no time, and with the help of sleep training, you’ll finally be able to sleep again soon. Better sleep is ahead! 

4-Month Sleep Regression Signs 

Although every baby is different, here are some common signs that your little one is going through the 4-month sleep regression: 

  • Increased fussiness
  • Difficulty falling asleep
  • Trouble sleeping through the night 
  • Difficulty falling back to sleep once woken 
  • Disrupted nap schedule 

What Causes the 4-Month Sleep Regression 

There are many developmental changes that your little one is going through that can contribute to the 4-month sleep regression. Here are some common causes: 

Developmental changes

Your little one is growing faster than we can even wrap our brains around! During the first 3 years of life, they’re forming over a million neural connections in their brain per second during sleep. They’re going through so many developmental changes. One of the most significant is a biological change in sleep patterns that typically happens between 12-16 weeks. Adult-like sleep stages string together into “sleep cycles.” These cycles last 60 -120 minutes during the night. After each sleep cycle, your baby’s body will come to a light stage of sleep and often slightly awaken. They will check in with their environment, making sure that everything is okay and their surroundings are unchanged. For some babies, each slight awakening turns into a major struggle. These babies usually fell asleep in mom or dad’s arms, at the breast or bottle, or being rocked.

They’re changing rapidly- learning motor skills, teething, growing, and advancing both physically and mentally. They may even be learning to roll or flip over. All of this is overwhelming to them- no wonder their sleep schedules are messed up!

Lack of routine 

Developing a bedtime routine is so beneficial to your little one (and you- the consistency of a bedtime routine will make your life easier!). If you haven’t implemented one yet, now is the time. Having a solid bedtime routine encourages your little one to develop healthy sleep habits from a young age. The familiarity of their routine will help your little one develop their sleep pattern to be more consistent and ultimately smoother for the whole family. As they get older, there are tons of fun bedtime activities for toddlers that can even make bedtime more fun for your little one to experience less bedtime resistance

More aware of their surroundings 

Your baby is starting to pick up more and more of their surroundings. They’re developing their observational skills and absorbing all the world has to offer from their lens. All of this is so exciting to them- making it much harder to fall asleep! 


Having a sick baby is so hard! It can feel like it’s thrown a wrench into their sleeping habits. There are ways to sleep train while your baby is sick, but don’t be too hard on yourself. Focus on your baby’s recovery, and then you can get things back to normal. 

Separation anxiety 

Separation anxiety is common in babies and toddlers. It’s completely normal for your little one to experience separation anxiety- as you continue to work through these feelings with your little one through sleep training, they will be able to develop a secure attachment.  

How to Handle the 4-Month Sleep Regression

Stay consistent 

It may be tempting to give up on routine, but staying consistent in your waking and sleeping routines will help your little one get back on track more quickly. When you break the routine, it ultimately confuses your baby and makes it much harder to get back to a good spot. This especially goes for nighttime feeds- if your baby is still feeding overnight, make sure to stay on schedule! My 3-12 Month Feeding and Sleep Schedules Guide goes into detail on feeding and sleeping schedules if you’re feeling lost. 

Avoid screen time at least an hour before bed

Avoid sitting them in front of a screen for at least an hour before you’re trying to get them to wind down. Being exposed to blue light too close to bedtime can delay the onset of melatonin and prevent your little one from falling asleep. 

Help your baby wind down 

There are tons of ways to help your baby become sleepy, making it easier for them to go to bed. There are many baby sleep products that can work wonders. Cuddling or rocking your little one can help them to relax, especially if they’re in an optimal sleep environment. A dark, quiet, comfortable sleeping space will help your baby fall asleep faster. This is one of the reasons why I’m such a huge advocate for a bedtime routine– you can make relaxing a part of bedtime every night to cue sleepy time!

Be patient 

It’s easier said than done- trust me, I’ve been there myself. Stay calm and patient during this regression and find comfort in knowing that this will pass soon! Although it’s technically called a “regression”, be excited about the progressions that your little one is making as they grow and develop into their own person. 

I hope these tips have helped you get through the 4-month sleep regression a bit more smoothly! Every baby is different, so if you’re not experiencing any relief from the 4-month sleep regression based on these tips, no need to panic! If you’re currently suffering through an endless stretch of sleepless nights, please feel free to reach out. I offer one-on-one sleep support to make bedtime easier for the whole family. Sleep training can be life-changing- you deserve to sleep through the night!

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