The 4 Month Sleep Regression: What You Need to Know

You probably first heard about the infamous 4 month sleep regression early in your parenting journey. If your baby slept well as a newborn, friends may have told you “oh, just wait until the 4 month regression”.  You weren’t quite sure what they were talking about….until now. 

I hear the same story over and over when families hire me as their baby sleep consultant: their baby slept beautifully until 3-4 months and then it all fell apart when the 4 month regression hit. Now, their baby is waking every 2-3 hours all night long and sometimes even more often. 

Why Does The 4 Month Sleep Regression Happen? 

The 4 month regression marks when a baby’s sleep pattern changes and goes from that of a newborn to much more adult-like. 

During the first 3 months of life, babies have a sleep cycle lasting about 50 minutes. They spend most of their sleep time in only 2 stages of sleep. Half is spent in an infant version of REM (“active”) sleep. This is the sleep where they twitch, smile, vocalize, or even open their eyes. The other half of their sleep is spent in NREM (quiet) sleep. This is the deep sleep when they are still, quiet, and can sleep through seemingly anything.

Starting around 3-4 months of age, the sleep cycle becomes more adult-like, lasting 60-120 minutes. Babies begin to spend time in all 5 stages of sleep, meaning they spend much more time in light sleep than they did as newborns. 

 Now, they move through all 4 stages of NREM sleep before finally moving into REM sleep. This cycle repeats all night long with micro-arousals between sleep cycles. As adults, we are so adept at putting ourselves back to sleep during these micro-arousals that we don’t even realize we ever so briefly woke several times during the night. Babies, however, often need help getting back to sleep. 

The truth is that this isn’t so much a 4 month sleep regression as it is actually a 4 month sleep progression. Your baby’s brain is maturing and that is a good thing! 

What Does The 4 Month Regression Look Like?

Regardless of whether you consider it a regression or progression, the 4 month sleep regression is a challenge!  This regression can start as early as 12 weeks and as late as 5 months. Most commonly it starts at 3.5-4 months of age. 

The 4 month sleep regression usually feels like finally getting your baby to sleep for a nap only to have them waken a short time later. It is common for naps to be as short as 20 minutes. During the night, babies may wake as often as ever 1-2 hours. That brings us to the big question….

How Long Does The 4 Month Sleep Regression Last?

Well, I have good news and I have bad news. We will start with the bad news: it technically lasts for forever. Because the 4 month regression involves a permanent change to the way the brain sleeps, it doesn’t just pass like the later sleep regressions do. 

Now, for the good news: the way the brain sleeps does not change, but it is quite possible to turn the short naps into long naps and get rid of the frequent night wakings.

Would you like another piece of good news? All babies experience the regression differently. Some are only mildly affected and start sleeping well again in as little as 2-3 weeks. 

Typically, these are babies who had independent sleep skills before the regression started. Babies who did not  yet have the ability to fall asleep on their own are usually more significantly affected by the regression and need to learn a new way of falling asleep in order to stop waking multiple times during the night. 

10 Tips For Handling The 4 Month Regression

The ultimate key to surviving the 4 month sleep regression is to make a plan to teach your baby a new way to sleep. But in the interim, while you are creating your plan, there are a few things you can do to keep your sanity. 

  1. Make sure baby is getting enough sleep. At 4 months of age, babies need the chance for 14-16 hours of sleep a day. Now, they may not take all the sleep you offer (thank you, our friend sleep regression!), but it is important to offer an 11-12 hour night and 3-4 naps.  Overtired babies have a much harder time falling and staying asleep than rested babies. 
  2. Make sure you are offering sleep at the correct times. At 4 months of age, you want to offer a nap 1.5-2.5 hours after you baby wakes up. If a baby stays up too long between naps, it just becomes harder for them to fall asleep. 
  3. Manage your expectations. Short naps are frustrating, but they are less so when you expect them. Know that long 1-2 hour naps just are not likely to happen right now. Having realistic expectations for your baby’s age and stage can keep you from being disappointed day after day by short naps and night wakings. 
  4. Make sure your baby’s room is sleep friendly. Whether sleeping in your room or their own room, make sure your baby’s room is dark and cool. When in doubt, go darker. White noise (max 50 decibels) may also be helpful. 
  5. Help your baby back to sleep. If your baby does not know how to fall asleep independently, your baby will likely need to be helped back to sleep at each waking. Unless you have a plan and are officially ready to start sleep training, going ahead and helping your baby right back to sleep will maximize sleep for each of you. Sleep training half heartedly will just frustrate both of you.
  6. But first, make sure your baby is actually awake! Often, we jump at the first peep we hear and inadvertently wake a sleeping baby. Oops! We want to be in the business of decreasing wakings, not increasing them. Babies are noisy, wiggly sleepers. They can often look and sound awake when they are actually still sleeping. Before you pick up (or even just talk to) your baby, wait just a few minutes to make sure they are fully awake. You may surprise yourself and find it was a micro-arousal or REM sleep and your baby slips back into quiet sleep all on their own. 
  7. Maximize daytime feedings. At 4 months of age, babies are undergoing a lot of developmental changes. They are becoming increasingly alert and more interested in the world around them. This can take a toll on their feedings because watching the world becomes so much more fun than eating. Often, this will result in them shifting calories to the nighttime. This nighttime calorie shift then results in them getting used to these nighttime calories and eventually expecting to eat multiple times at night. When added to the 4 month sleep regression, this is a double whammy. Fix this by encouraging full feedings during the day. 
  8. Work on putting your baby down awake at bedtime and first nap. You ideally want your baby to be drowsy but alert enough to be aware they are being placed into their crib. Why? When they fall asleep feeding or rocking and wake flat on their back in a crib, this is enough to rouse them to full alertness between sleep cycles. Imagine yourself falling asleep on your bed and waking up on the kitchen floor.  Weird, right? You wouldn’t just roll over and go back to sleep. You’d get up and go back to your bed. The same goes for babies: they will need the feeding or rocking in order to fall back asleep. Cue baby crying “Mama, I’m awake and need you to rock me”. You will likely have more failures than successes in the beginning and that is okay! It is all about practice not perfection. 
  9. Research all things baby sleep and sleep training and create your plan to teach your baby new ways of falling asleep. Most babies who struggle with the 4 month sleep regression are used to either feeding or rocking to sleep. This is not a bad thing in and of itself. However, it often becomes unsustainable when parents have only been sleeping in  1-3 hour chunks for months. So, what is an exhausted parent to do? Teach your baby a new way to fall asleep that does not require help from a parent. 
  1. Ask for help. The 4 month sleep regression can be exhausting. Sleep deprivation can be quite challenging for parents. Ask for help when you need it. Perhaps that help takes the form of a grocery delivery service or laundry service. Maybe it is the form of taking shifts at night with your spouse so each of you gets a solid chunk of sleep. Get creative and see what you can do to make the non-baby part of life easier for a while. 

 Implement Your Plan

If, after 2-3 weeks into the 4 month sleep regression your little one is still struggling with sleep and is unable to fall asleep without being fed/rocked to sleep, it is time to implement your plan and teach your baby a new way to fall asleep. 

While there is no such thing as “too late” to teach a baby a new way to fall asleep, it certainly is easier to do the younger the baby. The sweet spot is 4-6 months of age as they are old enough to successfully sleep train and young enough the feeding/rocking habits aren’t as ingrained as they are with an older infant or toddler. If your baby feeds or rocks to sleep every night, it is very unlikely they will suddenly decide to start falling asleep all on their own in the next few weeks or months. 

In sum, the 4 month sleep regression is a challenging time. But, the good news is that you don’t have to live with short naps and night wakings for forever. By making a plan to survive the regression and to teach your baby a new way of falling asleep, you can be assured that better sleep is on the horizon. 

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