The four-month sleep regression is agreed upon by almost everyone. You’ll hear me refer to this as the four-month sleep “progression.” A regression is defined as “reversion to an earlier mental or behavioral level,” and that’s the opposite of what your baby is experiencing. You may not believe me if you’re in the heat of it, but this is actually a great sign that your baby is developing normally.
Understanding Your Baby’s Sleep
To understand what’s happening to your baby during this stage, first you need to know a few things about sleep in general. Here’s the science-y part of this developmental stage.
At first glance, sleep seems simple; you are either asleep or you’re not. In contrast, sleep has four different stages, and they make up the “sleep cycle,” which we go through several times a night, adults and children alike.
Stage 1 is the initial stage we are all familiar with where you can feel yourself drifting off, but don’t really feel like you’ve fallen asleep yet. Anyone who has ever seen their partner nodding off in front of the TV, told them to go to bed, and gotten the canned response of, “I wasn’t sleeping!” knows exactly what this looks like.
Stage 2 is considered the first “true sleep” stage. This is where you tend to realize, once woken up, that you were actually sleeping. For anyone taking a “power nap,” this is as deep as you want to go, or else you’re going to wake up groggy.
Stage 3 is deep and regenerative. Also known as “slow wave” sleep, this is where the body starts repairing and rejuvenating the immune system, muscles tissue, energy stores, and sparks growth and development. Your baby NEEDS deep sleep to grow and development.
Stage 4 is REM (rapid eye movement) sleep. This is where the brain starts to kick in and consolidates information and memories from the day before. It’s also the stage where we do most of our dreaming.
Once we’ve gone through all of the stages, we either wake up or come close to waking up, and then start over again until the alarm goes off. For a baby they are often fully waking up when it’s time for a feed.
Why does this sleep reorganization disrupt sleep?
Newborn babies only have 2 stages of sleep; stage 3 and REM, and they spend about 50% of their sleep in each stage. This continues until about the third or fourth month, when there is a reorganization of sleep. During this developmental leap, a baby embraces the 4-stage method of sleep that they’ll continue to follow for the rest of their lives.
When this reorganization takes place, baby moves from 50% REM sleep to 25% to make room for the first two stages. So although REM sleep is light, it’s not as light as the two new stages that they’re getting used to, and with more time spent in lighter sleep, there’s more of a chance that baby’s going to wake up.
Your baby is supposed to be waking up (gasp) – yes you heard me correctly. It is normal and healthy for your baby to wake up throughout the night, just as adults do. There is no such thing as sleeping through the night.
What is the difference between adult and baby sleep?
As adults, we can identify certain comforting truths that your baby might not be privy to. When we wake in the night, we’re able to recognize that, “Hey, I’m here in my bed, it’s still nighttime, my alarm isn’t going to go off for another three hours, and I’m reasonably certain that there are no monsters lurking under my bed. I can go back to sleep.” Usually our waking is so quickly that, the next morning, we don’t even remember the brief encounter with consciousness.
A four-month-old baby lacks these critical thinking skills. To a four month old baby who fell asleep at her mother’s breast, the reasoning could go much more to the tune of, “OK, last thing I remember, there was a familiar face, I was having dinner, and someone was singing me a soothing song. Now I’m alone in this dark room, where the heck am I”?
I like to think of it like this – imagine going to sleep in your bed and waking up in the front lawn. You would have a few moments of panic. Your baby has the same feeling.
When baby naturally wakes and realizes that moms not around, and they’re not entirely sure where they’ve gone, the natural response is to do a little freaking out. That stimulates the fight-or-flight response and, next thing you know, baby’s not going back to sleep without a significant amount of reassurance that everything is OK.
The other major contributor to this “progression” is HOW parents have been putting their baby to sleep, up this point. Common strategies for newborns are pacifiers, breast or bottle feeding to sleep, rocking, or holding. Parents often find that their “go to” way to get baby to bed suddenly doesn’t work. It’s often a moment of panic and the start of a cycle of desperation.
Why do sleep props stop working?
Now that your baby is spending more time in lighter sleep, they have a higher probability of waking up. These sleep props or sleep associations may be helpful in getting your little one to that initial nodding off stage, when baby wakes out of light sleep or at the end of a sleep cycle, they cannot get back to sleep without some outside help. Cue the fight-or-flight, the crying, and the adrenaline. When this starts happening every half an hour, parents can find themselves exhausted and not sure what to do.
What can you do to help your baby “progress” without the struggle?
Darkness: If you haven’t already darkened your baby’s nursery or sleeping space, it’s time to do so. Even the slightest amount of light can make it harder for baby to fall asleep and stay asleep. Our sleep cycles and circadian rhythm and the associated sleep hormones (melatonin) are very much driven by light. When your baby is exposed to light during sleep, it tells their brain it’s time to be alert and hormones are released accordingly (the opposite of what you want for sleep). Invest in some quality blinds or curtains. You can also DIY this with black trash bags, dark sheets, or a blanket.
Newborns and infants are not afraid of the dark, so I don’t recommend a night light or any type of light for sleep.
White noise: The other nemesis of daytime sleep is noise. Whether its Amazon ringing the doorbell, the dog barking, or something falling on the floor three rooms away. With baby spending more time in lighter sleep, noises will startle them easily and wake them up, so a white noise machine is a great addition to your nursery.
White noise is not a sleep prop because it doesn’t require you to do anything additional after turning it on. It’s a constant and it can be on as long as baby’s sleeping. Avoid music due to the fluctuations in tones and general distraction. Remember to keep the noise at a reasonable volume – it doesn’t need to sound like a jet engine is in the bedroom for it to work.
Pro tip: if you have other children in the house, try adding a white noise machine to the hallway outside baby’s room. This adds another level of noise protection.
Bedtime routine: A solid routine is an essential component to getting your baby sleeping well. Try to keep the routine to about 4 or 5 steps, and no longer than 30 minutes. Never end your routine with a feed because you risk baby nodding off at the breast or the bottle, and that will create the dreaded “association” of feeding to sleep.
I suggest you place the bedtime feed at the beginning of the routine and plan the songs, stories, and getting into PJs towards the end. The goal is laying baby down in their crib or bassinet totally awake. If baby starts to fuss, try offering comfort and soothing from the crib side. This is good practice for baby, as they continue learning how to self soothe.
Avoid Overtiredness: If you’re noticing baby getting fussy before bedtime, you’ve probably waited too long. Four-month-old babies should only be going 1.5 to 2 hours between naps and bedtime, and bedtime should be between 7 and 8 at night. If you are seeing heavy sleepy cues before bedtime – eye rubbing, fussing, glossy eyes – you’ve likely waited too long. Try laying baby down before you see these cues. Overtiredness is the cause for many sleep challenges – your baby’s body is literally fighting again itself because of hormones being released to maintain an awake state.
The Good News
Once you’re through the 4-month sleep regression, your baby will have officially moved into the sleep cycle that they’ll essentially be following for the rest of their life. Four glorious stages repeated multiple times a night.
By taking this opportunity to teach them the skills they need to connect sleep cycles together, independently, prop-free, without any need for nursing, rocking, or pacifiers, you’ll have given them a gift that they’ll enjoy for the rest of their young lives.
Some babies may struggle more with this transition. If you’ve tried the steps above and are still struggling, it’s time to reach out for help. Whether you decide a DIY approach to sleep training is right for you or you’d like to work with a baby sleep consultant, the choice is yours.
Don’t wait until you are desperate. Parents often tell me “I can’t believe I waited so long to get some help!” If you are considering hiring a baby sleep consultant, now is absolutely the time. Before I was a sleep consultant, I was a mom. I’ve been there mama. Time to get some sleep.