Countless parents come for help with their 4 month old’s sleep. Why? This article will explain why “good” sleepers sometimes turn “bad” around the 3 or 4 month old mark.
How your newborn baby sleeps in the early weeks
When a newborn sleeps, she cycles between “active” and “quiet” sleep (also known as REM and non-REM sleep), but does not have the distinctive stages of sleep she will have as she grows older and her brain matures. I will avoid too much technical talk because that’s one reason I made this website, so you won’t have to learn the whole history of sleep if you don’t want to (or can’t stay awake to!)), but if you are interested in knowing more about our biological rhythms and how we do sleep in more detail, I highly recommend the book, Solve Your Child’s Sleep Problems), even if you have no interest in “Ferberizing” (just skip that part and consider a no-cry method). Newborns spend a lot of their time in deep sleep, which is why it is hard to wake them up (even to eat!) in those early days, but they do startle when they cycle into “active” sleep, which is one reason swaddling your baby can be so effective.
4 month old sleeps (and sometimes as early as 3 months or as late as 5 months)…
We all go in and out of light and deep sleep. As adults, we might change positions, look at the clock, or reposition our pillow. Up until now, you may have rocked your baby or simply given him a pacifier and he slept for hours without waking up. Well, at 3 or 4 months old, your baby is now sleeping more like an adult. Now when she falls asleep, she does not enter deep sleep right away and if you lay her down before she is in deep sleep, she is likely to wake up and you will start all over helping her to fall back to sleep again and again.
4 month olds enter deep sleep…
Initially in the night, your 4 month old will enter deep sleep relatively quickly, within 30 minutes (this changes as we get older). However, as I said, we all cycle in and out of light and deep sleep. A child’s sleep cycle is about 45-50 minutes. So, your baby will briefly awake 45-50 minutes after she has been asleep. To put that in perspective, if you are holding your baby to sleep, you would need to hold her for at least 30 minutes to make sure she’s in deep sleep and then she might wake up 15 minutes later. Sound familiar?
Overall, though, your baby’s deepest sleep is in the early part of the night, so after that first sleep cycle, she might sleep just fine for a few hours. So, you’re golden right? Just hold her for an hour? Nope!
4 month old sleeps the rest of the night…
The technical definition of “sleeping through the night” is 5 hours of continuous sleep (i.e. no feedings) and many babies can/will do this by 2 or 3 months old. The beginning of the night is your baby’s deepest sleep and after the first 5 hours (if not sooner, depending on just how challenging he is), he will cycle between light and deep sleep, but not as deep as the beginning of the night. This is where the problem of sleep associations really come into play. If your baby needs your help to go to sleep in the beginning of the night, sometime after midnight or so, he will continue to need your help every 1 or 2 sleep cycles (that means every 45 to 90 minutes or as I often hear, every 1-2 hours).
Between 4-6 a.m., approximately, is the lightest sleep of the whole night (parents’ complaints alone make this true, in my experience, aside from my reading). In the very early morning hours (about 30 minutes to an hour before waking up), he will again go into the very deep sleep.
Although babies commonly wake up early, be sure it is truly their waking up time and not just this lighter sleep and that they are having trouble sleeping. You might notice they want a “nap” just 30 or so minutes after “waking up”. What you experienced was a night waking, not starting the day.
4 month old sleep regression
You might have heard about the 4 month sleep regression and wonder if your baby will go back to sleeping well. Some parents will be one of the lucky few whose baby will go back to sleeping well in 2-4 weeks, however, not all of us will be that lucky. For example, I find that babies who need a pacifier to sleep where you are replacing it many times per night do not stop needing that pacifier to sleep. You might get lucky and not have to replace it 10 times (maybe “just” 3-4), but maybe not. It is usually better to solve the root of the problem than to hope you are one of the lucky ones. So, maybe wait a few weeks, but if things aren’t better, plan to make changes. I talk to parents of 8 month olds and even 20 months old who are still waiting for their “baby” to grow out of their sleep problems.
4 month olds sleeping through the night…
How can you help your 4 month old sleeping through the night? Read this website (free article updates via e-mail is a good choice), be sure to check out my free guide, 5 Ways to Help Your Child Sleep Through the Night and/or get a detailed step-by-step baby sleep guide, which includes e-mail baby sleep consultations, to answer all those “what if?” questions.
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