What Is The 4-Month Sleep Regression?

One day, your infant is sleeping like, well, a baby. The next, the 4-month sleep regression hits. Here's what you need to know.

It’s been months since your little bundle of joy arrived, and even though there have been some late night feedings and nap time wake-ups, this whole sleep thing isn’t as bad as people warned you about. Your baby is sleeping, your partner is sleeping, you are sleeping. What’s all the drama about with this sleep deprivation thing? Well, fast-forward three months, and you’ll see. It’s called the 4-month sleep regression, and it is the end of your baby’s dreamy sleep cycle.

READ MORE: The Fatherly Guide to Sleep

A sleep regression is basically just fancy speak for the occurrence of natural sleep patterns changing and causing babies to wake more frequently, sleep less soundly, and transition with napping schedules. At four months, most little ones undergo the first (of several) sleep regressions that most commonly take place at the ages of four months, nine months, and 18 months.

Several things can cause a sleep regression, but the shift in sleep habits are most often attributed to natural growth and development in a baby (such as crawling and teething) that create changes in sleep patterns that will contribute to these developments. In other words, your baby growing up can mean less sleep for you. But it doesn’t have to. You can diminish the impact of sleep regressions by preventing poor sleep habits and avoiding an inappropriate sleep schedule that makes bad situations worse.

At four months of age, babies start to get busy for the first time. They begin rolling over, squirming, and gaining more motor control. They also start to sleep less. At this time, babies sleep closer to eight hours at night uninterrupted and can get away with four hours of napping spread throughout the day — instead of getting 16 hours of sleep sporadically spread throughout the day and night (as is the case with a newborn).

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Babies at this age need less sleep because they are entering the phase of more normalized, adult-like scheduling that they’ll adhere to for the rest of their lives — plus their schedule can now differentiate between night and day. Gone are the times of the womb-sleep schedule.

Previous to four months a baby is still on the same schedule they were on in uterine, and can immediately enter a deeper non-REM sleep, according to certified infant and child sleep consultant Pam Edwards.  This is why you have been able to rock or nurse your 2-month-old baby to sleep and just put them down for a nap wherever — the car, the living room, a football stadium — without any disturbances waking them up. But at four months, babies don’t enter deep sleep as quickly (like an adult) and can easily be stirred within the first 30 minutes of falling asleep.  So rocking, holding, and singing to a baby becomes stimulating — not sleep-inducing. Reducing all distractions, noise, light, and keeping a steady room temperature is imperative to beating a sleep regression.

In addition to controlling your child’s sleep environment, it’s important to get your baby on your schedule, and stick to it, since this will be similar to the schedule they are on for the rest of their lives. A baby who was previously sleeping in until 7 or 8 AM will begin to wake up at a more natural “sunrise” hour — around 6 or 7 AM. Instead of hoping that a later bedtime will promote them to continue sleeping in, put them to bed earlier and guarantee a (full) good night’s sleep. This will prevent a shorter sleep cycle from creating an overtired baby who will in turn wake up even earlier, more frequently, and grouchier. Get on board with the “early to bed, early to rise” pattern and stick to it — anything less is going against baby’s natural sleep rhythms, according to family sleep consultant Hailee Schollaardt.

Aside from natural adjustment to the circadian world around them, a baby’s physical development also contributes to changing sleep pattern. At four months, most babies become more mobile — making swaddling unsafe. But swaddling still promotes sleep, so you’re stuck between a sleepsack and a hard place, trying to find the sweet spot to keep your baby comfortable and — more importantly — asleep. This means that the swaddle is no longer safe to use.  The downside to this is that Simply unswaddling a baby and moving them to a sleepsack will cause them to begin waking up at night or start to have difficulty falling and staying asleep for naps. In this case Edwards suggests trying the Baby Merlin’s Magic Sleepsuit (until they start rolling in their sleep).  “It’s a fantastic tool for babies who aren’t able to be swaddled but just aren’t ready for a sleepsack quite yet,” writes Edwards in a post on the Wee Bee Dreaming sleep consulting site.

Promoting an early bedtime, creating a calm sleep environment, getting good naps, and switching up the way you swaddle and help you to prevent any of your baby’s sleep regressions from turning into a lack of sleep for your family. Just remember that sleep really isn’t that tricky — we all need it, and your baby wants it. Provide the schedule, environment, and guidance for good rest and it will come (not always, but it will come).