Newborns

Navigating Sleep During the 4-Month Sleep Regression

The first year of your baby’s development is marked by rapid growth and transformative development. It can often feel as though every 4-6 weeks brings new sleep problems and another “regression” to navigate. Of all the developmental milestones your little one will encounter in the first year, the maturation of their sleep cycles, which occurs around 4 months old, is the only one intrinsically linked to sleep. While other milestones might indirectly influence sleep patterns due to cognitive and physical growth, this particular change directly shapes your baby’s sleep stages, cycles, and the balance of sleep hormones.

See here for our wake window guide.

In popular discussions and many parenting forums, the 4-month sleep regression is frequently painted in a negative light, but we challenge that perspective. With myriad blogs and books cautioning parents about this period, it’s easy to approach it with trepidation. However, we encourage a shift in perspective: see it as a celebratory milestone. For many, the term “sleep regression” implies a setback, but the truth is, your child is making monumental strides in their development. A more fitting term for this phase might be the ‘4-month sleep progression’ or ‘4-month sleep evolution’.

In this blog, we’ll explain the science behind this sleep phase, highlight its signs, discuss its duration, and offer tips to support you and your baby as you navigate this important milestone.

The Science Behind the 4-Month Sleep Regression

As your baby’s brain grows, their sleep patterns undergo significant changes. Initially, a newborn’s sleep is primarily characterized by two stages: REM (Rapid Eye Movement) sleep, which is associated with dreaming, and non-REM or deeper sleep. However, around the 4-month mark, your baby’s sleep patterns begin to resemble that of adults, with multiple stages of sleep—both REM and non-REM.

One of the most significant changes during this period is the establishment of the circadian rhythm. This internal clock helps regulate sleep-wake cycles, aligning them more closely with day and night. As a result, your baby starts to have a more predictable pattern of daytime wakefulness and nighttime sleep.

Understanding Your Baby’s Sleep Cycles

As your baby grows, their sleep cycles evolve. In the early months, each cycle for infants can be as short as 50 minutes. Over time, these cycles gradually lengthen. By around 3 years old, your child’s sleep cycles will approach the adult duration of approximately 90 minutes. At the end of each cycle, there’s a brief period of semi-awakening. These brief wake-ups serve a crucial evolutionary function: they allow the individual, whether baby or adult, to momentarily check their environment and ensure it’s safe before transitioning to the next sleep cycle. While adults often roll over and return to sleep, babies may have varying abilities to do so without external assistance, which can help explain why your little one may be restless and having a hard time staying asleep.

Within the realm of sleep training, the term “linking sleep cycles” describes the ability of a baby to transition smoothly from one sleep cycle to the next. It’s common to hear discussions about babies needing to “learn” to link these cycles, especially when they face challenges in doing so. While this terminology is widespread, it’s essential to delve deeper into what it truly means. Sleep cycle progression is fundamentally a natural physiological process. It’s not something that can be “taught” in the way we teach skills like tying shoes or reading. However, we can certainly guide and support babies in their natural sleep journey. The ability to self-soothe and transition between sleep cycles without fully waking is influenced by a myriad of factors, including sleep associations, environment, caregiver interaction, and individual temperament.

The Role of Sleep Hormones

Concurrently, there’s a shift in the hormonal balance that governs sleep. Melatonin, often referred to as the “sleep hormone,” plays a crucial role in signaling to the body that it’s time to rest. On the other hand, cortisol, while commonly known as a “stress hormone,” has another essential function: it helps us wake up and stay alert. As your baby’s sleep matures, the production and regulation of these hormones become more defined.

Recognizing the Signs of the 4-Month Sleep Regression

Many parents can be caught off guard by the 4-month sleep regression. It’s not uncommon for a 3-month-old to start sleeping for longer stretches during the night, so it comes as a surprise when suddenly that same little one starts waking up every 1-2 hours throughout the night again. The abrupt change is a primary indicator that your little one has hit this developmental milestone.

Here are some other signs to watch out for:

Fussiness before sleep
Not settling as easily
Restlessness during sleep
Frequent night waking

It’s worth noting that these signs primarily relate to nighttime sleep. At this age, short naps are still very normal. So, if your baby’s naps seem brief, it doesn’t necessarily indicate they’re going through the 4-month sleep regression.

How Long Does the 4-Month Sleep Regression Last?

The 4-month sleep regression is significant, and like all developmental milestones, the duration of the sleep disruptions it brings can vary from one baby to another. While some might breeze through this phase with minimal disturbances, others might experience more pronounced changes in their sleep patterns. Not all babies will show overt signs of this sleep regression, but it’s important to note that they all undergo this developmental transition. Some might just internalize or process it differently, leading to minimal observable changes in their sleep patterns.

Navigating the 4-Month Sleep Regression

The 4-month regression can be a challenging time for both parents and babies. However, with a blend of understanding and thoughtful strategies, this period can be navigated with grace and confidence.

Establish a consistent bedtime routine: Predictable sleep routines, both pre-bedtime and pre-nap, can signal to your baby that it’s time to wind down. Consistency in these routines offers a sense of security, making sleep transitions smoother.
Familiarize with the crib: Encourage your little one to explore their crib during the day, allowing them to associate it with comfort and security. This familiarity can pave the way for smoother transitions at night. Additionally, give your little one some practice going into their crib awake and settling to sleep there. This can help them learn to settle to sleep under the same conditions they will experience throughout the night.
Darken the Room and add white noise: Sunlight can kickstart cortisol production and set the internal clock to an early wake-up. Blackout curtains can promote deep sleep, and prevent early morning sunlight from disrupting your baby’s sleep. Additionally, white noise can help create a consistent signal to your baby that it’s sleep time.
Monitor Wake Windows: One benefit of this milestone is that it means you can start to establish your baby’s sleep schedule. While your little one may not yet be ready to follow a sleep schedule consistently, do your best to ensure they’re ready for sleep when you put them down. Ideally, with the right balance of sleep pressure so they’re not too tired, or not tired enough. While some babies might not show clear signs of sleepiness, adhering to age-appropriate wake windows can help them fall asleep more easily and sleep for longer durations both for naps and at night. At this age, your baby needs 12-16 hours of sleep in a 24-hour period, with approximately 3-4 hours of that sleep occurring during the day through naps.
Pause Before Responding: Babies can be noisy roommates! Before rushing in when your baby wakes, take a moment as they might just find their way back to sleep. This isn’t about leaving them to cry it out, but rather allowing them a chance to discover their own capabilities.
Understand Nighttime Feeding Needs: At 4 months, many babies still require nighttime feeds. It’s not uncommon for infants of this age to need a feed every 6 hours or even more frequently during the night. The frequency of these feeds often correlates with their daytime intake which often increases during this time as 4 months of age is a common time for a growth spurt to occur. If your baby doesn’t eat enough during the day, they will make up for it at night. As they’re becoming more interested and aware of their surroundings, 4-month-olds can sometimes become easily distracted during daytime feeds, which might influence their nighttime sleep patterns. To mitigate this, consider establishing a consistent feeding schedule during the day. If your baby seems easily sidetracked during feedings, a calm, quiet room can help them focus. Always remember, if there are any concerns regarding your baby’s weight or feeding patterns, it’s best to consult with a pediatrician.
Expand your comforting methods: If you always use one method to soothe your baby during wake-ups—like rocking or feeding—try introducing other techniques. Even letting another caregiver step in can be beneficial. This ensures your baby learns various ways to settle, preventing over-reliance on one method. However, while variety is good, avoid using every method at once for each wake-up.
Patience is key: The definition of “‘sleeping through the night varies,” but at this age, it most often means sleeping for a stretch of about 5-6 hours without waking for a feed. Every baby is different, and some 4-month-olds may sleep longer stretches, and others may wake more frequently. While some sleep consultants might advocate for sleep training at this age, we believe that sleep training has better outcomes when your little one has had more time to develop the gross motor skills to be able to find ways of self-soothing, and for their sleep patterns to settle into a more predictable and consistent rhythm. However, this doesn’t mean you can’t do anything to help your little one sleep better before then. Our Batelle Babies program can help you to set up the perfect foundation for healthy sleep habits, which often leads to better sleep for the whole family.