The Four Month Sleep Regression 

As a professional sleep consultant, I hear the term “regression” used in regards to just about every imaginable circumstance. Essentially if baby doesn’t sleep well for a couple of nights, parents start dropping the ‘R’ word. Some people subscribe to the idea that there’s an eight month regression, a 9 month regression, a 1 year regression, as well as teething regressions, growth spurt regressions and so on. Others see these as simple hiccups caused by extenuating circumstances. Now the four month sleep regression, everybody agrees on and for good reason. It’s the real deal, and it’s permanent.

In order to understand what’s happening to your baby during this stage, first you need to know a few things about sleep in general. So here’s the sleep science part of things, explained in plain English.

Many of us just think of sleep as an on-or-off situation. You’re either asleep or you’re not!  But sleep actually has a number of different stages, and they make up the “sleep cycle,” which we go through several times a night.

  • Stage 1 is that initial stage we’re 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 people tend to realize once woken up, that they 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.
  • 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. Stages 1 through 4, all night long.

So what does this have to do with the dreaded regression we were talking about originally?

Well, newborn babies only have 2 stages of sleep. Stage 3 and stage 4 (REM), and they spend about half of their sleep in each stage. But at around the third or fourth month of life, there is a reorganization of sleep as they embrace the 4-stage method of sleep that they’ll continue to follow for the rest of their lives.

When this change takes place, baby moves from 50% REM sleep to 25% in order to make room for those first two stages. So although REM sleep is light, it’s not as light as these 2 new stages that they’re getting used to. Now with more time spent in lighter sleep, there’s more of a chance that baby’s going to wake up.

That’s not to say that we want to prevent or avoid baby waking up. Waking up is absolutely natural, and we continue to wake up three, four, five times a night into adulthood and even more in old age. As adults however, we’re able to identify certain comforting truths that 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 night time, my alarm isn’t set 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!” And we do. Usually so quickly that the next morning, we don’t even remember the brief encounter with consciousness.

A four month old baby of course, lacks these critical thinking skills. To a four month old who has been falling asleep at her mother’s breast for most of her short 4 month life, or drinking a bottle with daddy while dozing off, the reasoning could go much more to the tune of… “OK, last thing I remember I was having dinner. And someone whom I love very much, was singing me a soothing song about the Teddy Bears’ Picnic. Now I’m alone in this dark room, there’s no food or anyone to help me return to sleep!”

Now that Lily suddenly realized that Momma is no longer around, and she’s not entirely sure where she went, the natural response is to do a little freaking out. That stimulates the fight-or-flight response, and next thing you know Lily is not going back to sleep without a significant amount of reassurance that everything is OK.

That’s just one example of why things may seem to be going south once a baby reaches the age of 4 months. Many other things contribute to the 4 month fiasco, aka the four month sleep regression. I find that if up until this point parents have either been putting their baby to sleep with a pacifier, rocking or breastfeeding to sleep, or any similar technique where baby is helped along on the road to falling asleep…all of a sudden things make a turn for the worse, even with the best little sleepers.

Now that baby is spending more time in light sleep, and therefore has a higher probability of waking up, this suddenly becomes a much bigger issue. Sleep props or sleep associations can be very sneaky! Although they may be helpful in getting your little one to that initial nodding off stage, the lack of them when they wake up throughout the night means that baby is not able to get back to sleep again 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 in a pretty exhausting nightmarish situation.

So! The good news for anyone experiencing the dreaded Four Month Sleep Regression, is that it’s not in fact a regression at all. A regression is defined as “reversion to an earlier mental or behavioral level,” and that’s actually the opposite of what your baby is experiencing. This would be much more aptly titled the “Four Month Sleep Progression

Now onto the big question, what can you do to help your little one adjust?

  • First off, get all of that light out of baby’s room. You might think that baby’s room is dark enough, or that baby might not like the dark and that it’s comforting to have a little bit of light coming through the windows or seeping in from the hallway.
  • Nope! Baby’s room should be dark. I mean coal mine on a moonless night kind of dark. You can get creative here, it doesn’t have to be pretty right away. Tape garbage bags over the windows for now if you have to, cover them with tinfoil or a dark bed sheet. Newborns and infants are not afraid of the dark. They are however very responsive to light! Light tells their brains that it’s time for activity and alertness, and the brain secretes hormones accordingly. So we want to keep that nursery absolutely pitch black during naps and bedtime. For a more permanent (and better looking) solution, I recommend the EZ Blackout Window Coverings to all of my clients!  Check out this great (and very affordable) way to a dark room at
  • The other nemesis of daytime sleep, (and nighttime for that matter, although not nearly as often) is noise. Whether its UPS ringing the doorbell, the dog warning you that the squirrels are back and for sure going to attack the house this time, 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.
  • Bedtime routines are also an essential component to getting your baby sleeping well. Try to keep the routine to about 4 or 5 steps, and don’t end it with a feed. Otherwise, you risk baby nodding off at the breast or the bottle and that could create the dreaded “association” that we talked about earlier. Try to keep the feed near the beginning of the routine. Plan the songs, stories, and getting into PJs towards the end.  The whole process should be about 20 – 30 minutes long, and baby should go into their crib while they’re still awake.
  • If you’re noticing baby getting fussy before bedtime, you’ve probably waited too long. Four month old babies should really only be going about two hours between snoozes. Bedtime should be between 6 and 8pm.

Now, there are going to be regressions, actual regressions later on in your little one’s youth. Traveling, illness, cutting teeth, all of these things can cause your little one to have a few bad nights in a row. But when it comes to the four month “progression,” I’m happy to report that this is a one-time thing. Once you’re through this, 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 string those 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.

Of course some kids are going to take to this process like a fish to water, and some are going to be a little more resistant. Every baby is different! What may work really well for one, may not work at all for another. If sleep is growing increasingly difficult in your home, go ahead and use this link to schedule a free 15 minute sleep evaluation call with me!  This will allow us to talk about your own unique sleep challenges, and come up with some ideas for a solution that works for you and your family.