The four-month mark is a pivotal phase in your baby’s development that brings both challenges and opportunities for understanding and improving their sleep patterns. Many people use the term sleep regression any time that their baby goes through a couple days of sleep difficulties. However, a true sleep regression is characterised by factors including brain development, sleep cycle maturation and environmental awareness.

The Science Behind the Four Month Sleep Regression

Newborns initially sleep in 2 stages, called stage 3 and REM, with equal time in each. Around the third to fourth month, a sleep reorganisation occurs, transitioning them into the lifelong 4-stage sleep cycle. When this change takes place, baby moves from 50% REM sleep to 25% in order to make room for those first two stages. So although REM sleep is light, it’s not as light as these 2 new stages that they’re getting used to. Therefore, with more time spent in lighter sleep, there’s more of a chance that your baby is going to wake up.

That’s not to say that we want to prevent or avoid baby waking up. Waking up is absolutely natural, and we continue to wake up three, four, five times a night into adulthood and even more in old age. As adults, however, we’re able to identify certain comforting truths that baby might not be privy to. When we wake in the night, we’re able to recognize that, “Hey, I’m here in my bed, it’s still night-time, my alarm isn’t going to go off for another three hours, and I’m reasonably certain that there are no monsters lurking under my bed. I can go back to sleep” And we do. Usually so quickly that, the next morning, we don’t even remember the brief encounter with consciousness.

However, when your baby begins waking more throughout these lighter sleep stages they may suddenly realise that mum and dad are not around, and they’re not entirely sure where you’ve gone. This can stimulate a fight-or-flight response. Next thing you know, your baby isn’t going back to sleep without a large amount of reassurance that everything is ok.


Another significant factor approaching the four-month developmental stage, in my observation, is that parents have typically employed methods involving props. This could involve using a dummy, rocking, breastfeeding, or similar techniques to allow your baby to fall asleep before you put them down into their cot.

Now that your baby is spending more time in lighter sleep, and is more likely to wake, this can become a much bigger issue. Whilst sleep props and associations can be beneficial in facilitating your child’s entry into the initial sleep stage, they often pose challenges when they are absent upon waking. Your baby might be confused that they have woken in a different place to where they went to sleep, they are now looking for that prop to be able to get back to sleep again. If this starts happening every half an hour, parents may find themselves in a nightmarish situation.

Strategies to Support Your Baby Through this Transitional Phase

Firstly, eliminate all sources of light from your baby’s room. I’m serious about this. You might believe the room is sufficiently dark or that your baby prefers some light for comfort, perhaps from the windows or hallway. However, that’s not the case. Your baby’s room should be pitch black, as dark as a coal mine on a moonless night. Contrary to popular belief, newborns and infants are not afraid of the dark; rather, they respond to light. Light signals their brains to be active and alert, prompting the secretion of hormones. Therefore, it’s crucial to maintain absolute darkness in the nursery during both naps and bedtime.

Establishing effective bedtime routines is crucial for promoting healthy sleep habits in your baby. Aim for a routine comprising approximately 4 or 5 steps, avoiding concluding it with a feeding session. Ending the routine with a feed may lead to your baby falling asleep at the breast or bottle, fostering the undesirable “association” mentioned earlier. Instead, position the feed closer to the beginning of the routine and reserve activities like singing, storytelling, and dressing in pyjamas for the latter part. Ideally, the entire process should last about 20 to 30 minutes. You should place your baby in the cot while they are still awake.

If you’re noticing baby getting fussy before bedtime, you’ve probably waited too long. Four month old babies should really only be going about two hours between snoozes, and bedtime should be between 7 and 8 at night.

Now, if baby does wake up, and chances are, they probably will, try to give them a few minutes before you go in. I know this can be hard when they’re crying, but give them an opportunity to figure out the “get-back-to-sleep” process for themselves. If they’re still fussing after a few minutes, go in and offer a feed, but remember! Don’t feed to sleep! Place your baby back into their cot whilst they are awake! This will teach them to be able to settle to sleep in their correct sleeping place.

Now, throughout your child’s early years, there will be setbacks—real regressions sparked by events like travel, illness, or teething, causing a few challenging nights. However, when it comes to the four-month “progression,” I’m pleased to assure you that it’s a one-time occurrence. Once you navigate through this phase, your baby will have officially entered the sleep cycle that will essentially guide their nights for the rest of their life—four distinct stages repeated multiple times each night.

Seizing this opportunity to impart the skills necessary for seamlessly connecting these sleep cycles independently, without reliance on props, nursing, rocking, or pacifiers, is a gift that will benefit them throughout their early years. While some children effortlessly embrace this process, others may be a bit more resistant. If your little one falls into the former category, celebrate your success! For those in the latter camp, I’m here to assist in any way possible. Visit my website or give me a call, and we can devise a personalised program for your child.

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