Getting Through the Four-Month Sleep Regression

The four-month sleep regression is the most talked about regression. Do you know why that is? Because it is the only true sleep regression! You may hear other parents discussing all sorts of sleep regressions that simply do not exist. There is no 6-month, 8-month, 9-month, 1-year, 18-month, or whatever other “month” sleep regression you may have heard of. Parents are quick to label their baby as going through a sleep regression if they haven’t slept well for a couple of nights.

There are factors that can cause your child to have hiccups in their sleep, but these are not age dependent, they are caused by developmental milestones. Sitting up, standing, walking, and talking are all developmental milestones that have huge impacts on your child, and yes these can impact their sleep, but they don’t actually have anything to do with your child’s sleep biology. During developmental milestones, your child is often obsessively concentrated on their new skill that even when they should be sleeping, all they can think about is practicing sitting up, talking, etc.

I describe the four-month sleep regression as the only true sleep regression because it is the only milestone that is directly affecting the organization of sleep. In fact, I don’t want you to think of this as a regression at all! This infamous sleep regression is actually a PRO-gression. During this developmental milestone, your baby’s newborn sleep cycles are being re-arranged, PRO-gressing, into the sleep cycles that they will have all the way into adulthood.

Here is a little science into how sleep is arranged, so you can understand what your baby is going through during the “four-month sleep regression”.

We all go through stages as we sleep; four stages make up one sleep cycle. We go through several cycles as we sleep each night.

Stage 1: Falling asleep; that initial feeling of “falling” asleep. If you’ve ever sat next to your partner on the couch, they start nodding off in front of the TV, you tell them to head to bed, and they snap back, “I’m not sleeping!”, then you know exactly what this looks like. Anyone else? Or is this just what Friday night looks like at my house?

Stage 2: Light sleep; this is the first true stage of sleep where if you were woken up you’d be able to acknowledge that you had been sleeping.

Stage 3: Deep sleep; also referred to as “slow-wave sleep”. This stage is where the magic happens! Stage three sleep is where the immune system, muscle tissues, and energy is repaired, restored, and rejuvenated. This is also where growth and brain development occur!

Stage 4: REM (Rapid Eye Movement) Sleep; In this stage our brain processes information and memories. REM is a lighter stage of sleep than stage three and is where we do most of our dreaming.

Once we’ve gone through all four stages, we wake briefly and then start back into stage one, and the cycles continue this way until you wake fully in the morning (or the alarms goes off).

So! Let’s put this information into the context of the four-month sleep regression.

What is happening during “The Four Month Sleep Regression”?

A newborn only has two stages of sleep: stage three and stage four. They cycle through deep sleep and REM and spend about 50% of their sleep in each of these two stages. At around three or four months old this changes. It’s at this age where your baby’s sleep reorganizes into the four stages of sleep they will have for the rest of their lives. During this reorganization, your baby’s sleep will change from spending 50% of their sleep in REM, to only about 25%. In the early months of life, your newborn spends half of their sleep in the deep stage which is why they can sleep in very active, noisy environments easily. Although REM is a light stage of sleep, once your baby reaches this four-month sleep milestone they will be adding stages one and two to their sleep cycles which are much lighter stages of sleep. With all this light sleep going on, there is a much greater chance of your baby waking up.

BUT that’s perfectly fine! Babies wake up in the night, just as adults do, in between sleep cycles. As adults who have independent sleep skills, we wake up in between sleep cycles and quickly get ourselves back to sleep, often without any recollection of waking at all. For your young baby though, this is a different experience. For babies who have not learned independent sleep skills yet, they wake in between sleep cycles and immediately call out because they aren’t sure how to soothe themselves back to sleep.

It is very common that up until this point you may have used a pacifier, nursing, or rocking to put your baby to sleep. This may have worked just fine in the newborn stage, but it has not taught your little one the independent skills they need now that they have reached the four-month sleep milestone. If your baby fell asleep while you nursed and rocked them to sleep, when they wake after a sleep cycle, they will be alarmed that they are no longer in the comforting place they fell asleep in. They will certainly call out for you to come back to recreate that same environment they are accustomed to falling asleep in.

The reason that these strategies for getting baby to fall asleep are just now, at about four months, becoming a problem is because your baby is now spending so much more time in light sleep which results in a higher probability of waking up.

How do we get through it?

So we know why your little newborn sleeper has just become a little monster in the night, stealing your opportunity for restorative sleep too! Now let’s go through how we can get through this milestone.

First step is to make baby’s sleep environment completely dark. I’m talking can’t see my hand in front of my face kind of dark. Babies are not afraid of the dark; they do not have the imagination to believe that monsters are lurking in the shadows of their room. Even the slightest amount of light seeping into baby’s room can impact their sleep, causing them to fully wake between sleep cycles. Light signals to our brain to create daytime hormones that give us the energy to be alert and active. You want to have the same level of darkness for both naps and nighttime sleep.

Next, you’ll want to consider that noise may be waking your baby up while they are in light sleep. A newborn can often sleep anywhere, at any noise level it seems, and this is because they spend so much of their slumber in deep sleep. But once they reach this four-month milestone they will be much more sensitive to noises while they sleep. Dogs barking, doorbell ringing, birds chirping, whatever it is, a white noise machine can help to drown out these environmental noises that are causing your baby to wake too early from naps, or too early in the morning.

The final step in helping your baby through the infamous “four-month sleep regression” is establishing a bedtime routine. Having a simple, predictable routine is essential to getting your baby sleeping well. Your child will continue to have a bedtime routine forever. Think about it! You have one too! Whatever components you choose to incorporate into your child’s bedtime (bath, lullaby, storybook, infant massage, etc.) be sure to execute them in the same way and same order each night. A critical element is that you want your baby to stay awake during the entire routine so you can place them into their crib awake. It is so common to place a feed at the end of the routine, and this will often result in baby falling asleep at the breast or bottle (creating a sleep association). To avoid this, place the feeding near the beginning of the routine, so that there is about 15-20 minutes between their bedtime feed and when you lay them down in their crib.

If you find that your baby is a little fussy (or very fussy) during the routine then you’ve probably missed your window of opportunity. On average, a four-month-old can only handle two hours of awake time between sleep. So keep in mind when the last nap ended and place bedtime two hours after that. Ideally you want to aim for bedtime to be between 7-8pm.

Your child is going through a major reorganization of sleep so it will take a couple of weeks to work through it. Doing these few simple things can help your baby work through the changes effectively. If you just let the sleep cycles rearrange themselves and don’t make any efforts to help set your baby up for success on the other side of this sleep progression, there is a greater chance of having sleep struggles for many more months down the road.

As your child moves through the first few years, there will be some situations that cause a regression in sleep for a few nights; developmental milestones as mentioned earlier, illness, travelling, and teething. The good news is that establishing healthy sleep habits at the onset of this four-month sleep PRO-gression will give them the sleep skills they will enjoy throughout their childhood and beyond. Once you’ve gone through this, then you’re done. This is the only milestone that directly affects the development of sleep. Of course, your child’s sleep needs will change over the years, but those changes can be worked through with just a few tweaks to their schedule.

As with all things in life, every baby will handle the four-month sleep PRO-gression a little different from the next. Some babies take to the progression without skipping a beat, others are going to be a little more resistant. If you have a baby that handled it like a champ, then consider yourself one of the lucky ones and enjoy your sweet sleeper! If you have a baby who falls into the large group of babies that need a little help getting through, then I am happy to help. Reach out any time if tackling your baby’s sleep is becoming too overwhelming for you. You do not need to do this alone!