4 Month Sleep Regression
What causes the 4 month sleep regression?
At about 4 or 5 months old, many parents notice a dramatic spike in night wakes and sleep struggles. This is due to permanent changes in a baby’s brain and sleep patterns, when they form mature sleep cycles.
As a newborn, they transitioned between REM and deep sleep. Now, they cycle through 5 different stages of sleep like adults. These cycles usually last 1 to 2 hours each, and between cycles are partial or full wakes.
Sleep is a vulnerable state for humans, so the purpose of these wakes is to rouse us enough to readjust our body and check our surroundings. Adults don’t usually remember waking because we can go back to deeper sleep states without much fuss.
As you can see in the graph, the longest stretch of consolidated sleep is usually at the beginning of the night, with more light sleep stages in the early morning hours.
Can you avoid the 4 month sleep regression?
All babies go through sleep changes and brain development around this time, but not all babies start having sleep struggles. Babies that are naturally more sensitive to their environment and sensory stimuli are more likely to have a 4 month sleep regression.
For sensitive babies, it can be jarring to fall asleep in one place and find themselves somewhere else when they wake up between sleep cycles (for example, if you rock or bounce them to sleep and they wake in their crib). But even cosleeping babies can have a hard time at the 4 month regression, if they don’t know how to get comfortable and go back to sleep on their own.
4 month sleep regression signs
Here are the most common signs of the 4 month regression.
How long does the 4 month regression last?
Unlike other sleep regressions that are temporary, the sleep issues that start during the 4 month regression usually linger. Without intervention, sleep does eventually sort itself out. For a lucky few, sleep gets better around 12 months. For many others, it can take 18 months to 3 years for sleep struggles to pass on their own.
Tips to get through the 4 month regression
Out of desperation, some parents turn to cry it out (CIO) methods. Parental sleep deprivation can become serious and endanger you and your baby, so I understand why some people feel the need to resort to extreme methods. But there are compassionate ways to teach babies to move between sleep cycles.
The best method for your baby depends on temperament, sleep setup, parenting style, and sleep goals. If you want step-by-step guidance for gentle sleep training that’s tailored to your baby, check out my sleep packages. But here are some things all families can do to survive and thrive during the 4 month regression:
Feed hunger, not habit. Make sure your baby takes full feedings at night rather than offering milk just because they wake. They won’t be able to take enough daytime calories when they’re eating all night, and they’ll have to eat all night if they’re not getting enough calories during the day.
Lengthen wake windows. Around 4 to 5 months old, your baby will be ready to drop from 4 naps to 3 with 1.5 to 2 hour wake windows. It may be easier if the first wake window is shorter, getting incrementally longer throughout the day. Check out this article for more guidance around wake windows.
Keep a consistent bedtime routine. Having a routine that you follow every night creates a signal for your baby’s body that it’s time to relax. I have a whole article about bedtime routines because they’re so important, you can check that out here.
Work on independent sleep. Put your baby down awake in their sleep space so they can fall asleep without being nursed, bounced, etc. When they rouse between sleep cycles and are in the familiar place that they fell asleep, they’ll feel safe and confident to go back to sleep on their own. They’ll only wake fully for help if they’re hungry, soiled, uncomfortable, or in pain.
Inevitably, most babies that are used to being assisted to sleep will cry. This is where you will want to have a plan for your response. Cry It Out (CIO) and Ferber methods are commonly used, but I prefer compassionate methods that don’t involve withholding comfort or night feeds. You want your baby to trust that you’ll come when they need you. If you’re not sure where to start, you can check out my article about gentle sleep training.
Summary
The 4 month sleep regression is caused by permanent changes in a baby’s brain and the maturation of sleep cycles.
All babies experience these brain changes, but not all experience a sleep regression. Signs include more night wakes, struggles at naps and bedtime with falling asleep, short naps, and extra fussiness.
The habits you create now can last for many months, or even years. It’s important to establish sleep habits that are sustainable for your family in the long term.
Ways to get through this time are: make sure your baby takes full feeds, lengthen wake windows, create a consistent bedtime routine, and work on independent sleep with a responsive method that suits your baby’s temperament.
