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  • Writer's pictureAndrea

The 4 Month Sleep Regression

Updated: May 18, 2022

What is the 4 Month Sleep Regression and why does everyone seem to dread it? If you google 5 Month, 6 Month, 7 Month, 14 Month, 18 Month, etc etc Sleep Regression, you will find something. So why is the 4 Months Regression so notorious?

sleep regression
The 4 Month Sleep Regression

Most sleep regressions are related to meeting developmental milestones. Within a week or two, your baby should be sleeping well again; if previously she was a good sleeper. But with the 4 Month Sleep Regression (occurring between 3-4 months) , a true permanent shift in sleep occurs. There is a reorganization of the sleep cycle which can really throw your baby off.

So 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.

The Science Behind the 4 Month Sleep Regression

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. These stages 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 just feel yourself drifting off, but don’t really feel like you’ve fallen asleep. Anyone who has ever seen their partner nodding off in front of the TV, told them to go to bed, and received the 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 actually were 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 have gone through all of the stages, we wake up or come close to waking up, and then start over again until the alarm goes off.

Newborn babies only have 2 stages of sleep; stage 3 and REM. They spend about half their sleep in each stage. But at around the third or fourth month, 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.

Why Does This Transition Affect My Baby’s Sleep?

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. With more time spent in lighter sleep, there’s more of a chance that baby is going to wake up. Waking up is absolutely natural, and we continue to wake up multiple times a night into adulthood and even more in old age. When we wake in the night, we are able to recognize that, “Hey, I’m here in my bed, it’s still nighttime, and my alarm isn’t going to go off for another three hours. I can go back to sleep.” And we do. Usually so quickly that we don’t even remember the brief encounter with consciousness the next morning.

A four month old baby, of course, lacks these critical thinking skills. To a four month old baby who fell asleep at her mother’s breast, the reasoning may be more like, “OK, last thing I remember, there was a familiar, beloved face, I was having dinner, and Mom was singing me a soothing song. Now I’m alone in this room, I’m not being fed, and I’m no longer on a warm body.” The natural response is a little freaking out. That stimulates the fight-or-flight response which, make going back to sleep very difficult without a significant amount of effort.

The other major contributor to the regression is that up until this point parents have either been putting their baby to sleep with a pacifier, by rocking them, by breastfeeding them, or some similar technique where baby is helped along their journey into falling asleep. Now that baby’s spending more time in light sleep, this suddenly becomes a much bigger issue. These sleep props or associations may be helpful in getting your little one to that initial nodding off stage, but the lack of them when they wake up means that baby’s not able to get back to sleep again without some outside help. When this starts happening every half an hour, parents can find themselves in a tough situation.

Getting Through The 4 Month Sleep Regression

First off, baby’s room should be dark, like really dark. Newborns and infants are not afraid of the dark. They are, however, responsive to light. Light tells their brains that it’s time for activity and alertness, and the brain secretes hormones accordingly. This is for naps and bedtime.

Next, look into environmental noises that could be waking baby. Delivery person ringing the doorbell, dogs barking, or kids playing on the main level of the house. 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 will continue the association we talked about earlier. 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, with bedtime between 7 and 8 at night.

When baby does wake up in the night, give them about ten minutes before you go in. I know this can be hard when they’re crying, but give them an opportunity to figure out the “get-back-to-sleep” process for themselves. If they’re still fussing after ten minutes, go in and offer a feed. Try your best to keep baby awake through the feed.

It is almost impossible to avoid setbacks with your little ones sleep. Traveling, illness, teething, all of these things can cause a few bad nights in a row. But when it comes to the four month regression, I’m happy to report that this is a one-time thing. By taking this opportunity to teach them the skills they need to string sleep cycles together independently, prop-free, without any need for nursing, rocking, or pacifiers, you’ll have given them a gift that they will enjoy for the rest of their lives.

If you are wanting a bit more guidance, Whole Night Sleep Consulting is here to help!


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