Just when many of us finally feel we are getting some predictability with our newborn’s sleeping patterns…. BANG! Along comes the four-month sleep regression! In Wonder Weeks language, this equates to Mental Leap 4, which starts between 14.5-19.5 weeks. If you are experiencing this, you may find some comfort in knowing that this developmental leap is Universal. Frustration, exhaustion, tears, rocking in the fetal position, sleep deprivation, and screaming profanities is considered completely normal – and acceptable I might add! 🙂

So what is really going on? And what causes this ‘sleep regression’?

I feel it is somewhat unfair to refer to this as a regression. The first 12-24 months of a child’s life is full of learning, growth, development, and progression – otherwise referred to as developmental milestones.

During this time, your baby is learning so many cool new things about the world they live in; from the physical (rolling, sitting up, crawling, standing, walking, and teething), to emotional (separation anxiety), and neurological (perception, memory, understanding, logic, and reason). For this very reason, it is also not uncommon to experience sleep regression at 6 months, 8-9 months, 11-12 months, 14-15 months, 18 months and two years – often coinciding with mental and physical (developmental) leaps.

Specifically, around four months is when our little ones become much more aware of the world around them. They begin to communicate through babbling, can recognize familiar faces, start to roll, and EVERYTHING goes in their mouth (which is the way they explore their environment).

The real reason our babies’ sleep appears to ‘regress’  during such developmental milestones, is because like us, babies process information during their sleep. Their little brains are so busy practicing new skills, perceiving, exploring and experiencing in their waking hours, that they can have difficulty ‘switching off’ when it is time to sleep.


  • Baby. won’t. sleep. period
  • Increased difficulty falling asleep and staying asleep – despite a parent’s best efforts to rock, feed, hold or stick to a routine
  • Lots of drooling, fists in mouth
  • Crying, fussiness, and irritability during the day
  • Heightened clinginess, and obvious signs of distress when a parent (most commonly mom) leaves the room
  • Fussy on the breast or bottle, and increasingly distracted at feed times during the day
  • Change in appetite; either more or less hungry
  • Increased restlessness overnight e.g. squirming, crying out
  • More frequent night wakings due to an increased need to feed – commonly to compensate for distracted feeding during the day


At four months of age, our baby’s sleep patterns change from ‘newborn’ to ‘baby’  (i.e. more distinct cycles of REM/active sleep and Non-REM/deep sleep – similar to adults). This change can be unsettling for our babies as they learn to adjust to their new sleep cycle.

At this age, our babies are increasingly alert and become more aware of their environment. There is a transition toward more defined motor skills, improved vision, independence, and overall growth – not to mention, many begin teething!.

It is usually at times like this, many of us will experience some level of insecurity around our parenting ability. I know many breastfeeding mothers (myself included) who have considered introducing formula around four months of age – assuming this fussy behavior means that our babies are not getting enough milk from us. In many cases this is not the case, however, if you are concerned, I recommend consulting your local healthcare practitioner or lactation consultant.


  • Keep to a routine – Children thrive on knowing what to expect, and consistency makes them feel secure. Keep your sleep associations the same, and be sure attentive to your child’s sleep cues so they are not becoming overtired at these times (this will make it even more difficult for them to get to sleep and stay asleep). Remaining constant will give them the best chance at getting back on track as soon as that sun begins to shine again. An earlier bedtime (6:30 pm – 7:00 pm) may help prevent them becoming overtired, and dream feed scheduled 3 hours after bedtime may grant you some extra mileage overnight between feeds
  • Allow for flexibility. Know that consistency doesn’t mean rigidity – flexibility is important. The 80/20 rule is a good one to keep in mind. This maintains that; what we do 80 percent of the time establishes our habits and patterns – whether we are conscious of this or not. The remaining 20 percent affords families with some flexibility to accommodate for life’s unexpected turn of events such as illness, teething, developmental leaps and life transitions. If this means more naps in the carrier, stroller, or car than normal, then so be it. Or, if you have to sometimes rock your overstimulated child to help them fall asleep, it’s not the end of the world. Having your child sleep is always preferble to an overtired and sleepless baby + a frustrated and exhausted parent. Tip: Skin on skin can do wonders for connection at these times
  • Incorporate some wind-down time before naps and bedtime to give your child the best chance of relaxing before sleep. Sleep associations such as a dark room, white noise, swaddle, sleep bag, song, book and a cuddle goodnight will cue your baby that it is time for bed.
  • Keep your baby swaddled for bedtimes. Many babies still have an active Moro (startle) reflex at this age, and a swaddle can encourage sounder, longer sleep. Cease swaddling when your baby begins to roll.
  • Acknowledge your child’s feelings around sleep  Be prepared to spend a little more time sitting beside your baby and offering warm validation whilst they drift off to sleep at these times, they may need the extra security – e.g. “I can see you are having a hard time getting to sleep darling. It is safe for you to sleep now. I love you and I am here for you”.
  • Communicate to your baby if you are going to leave the room, put them down, change their diaper, pick them up, or leave them with someone else. Communicating your intentions in advance is not only respectful, but will encourage their cooperation – which can mean increased security, and fewer tears!
  • Download the Wonder Weeks app on your phone so you know when and what to expect from such developmental milestones (leaps) in the first 20 months – and how to respond to your baby’s behavioral and sleep needs during these times. Note: regression at these times can last anywhere between a few days to a few weeks.
  • Support your child’s need to cry. Provided that we have met our child’s primary needs, crying serves as an innate healing mechanism which allows children to obtain emotional equilibrium. When held in the attentive, loving arms of their parents, and not left to do so alone, crying promotes healing of past or present hurts, fears and trauma, and is an is an effective release for everyday stresses and tensions – especially beneficial in the early years when our children are evolving so rapidly, and transition, change, and developmental frustrations are inescapable.
  • Incorporate quality one-on-one time each day. No matter the age of your child, introducing at least 10-20 minutes of distraction-free, child-led “special” time each day can work wonders for connection and diffusing fear and insecurity – often heightened at times of developmental change (and mostly responsible for sleep difficulties). Although a four-month-old is unable to verbally communicate their chosen activity, remain attentive to their non-verbal cues, use plenty of eye contact, and allow the magic to happen!
  • Avoid sleep training whilst your baby is experiencing a milestone (especially cry it out/controlled crying).
    Remember to be patient, kind and sensitive to your baby’s needs. Extra cuddles and warm validation will make them feel understood, loved and secure…. And know (like everything else in the world of babies) that this too shall pass!

TIP: Be sure to rule out any medical reasons for frequent wakings, fussiness, or change in sleep patterns first and foremost before following the recommendations mentioned above, or embarking on a new sleep routine/program

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