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  • Writer's pictureSara Davis

Blog Series: How Sleep Develops Through the Ages (4-5 Months)

Welcome back to the next post in my blog series on Sleep Development Through the Ages. I decided to dedicate this entire post to 4/5 month olds because a) it’s one of my favorite ages and b) it’s one of the most common ages that parents begin to contact me in regard to their child’s sleep. This is the common refrain I hear:

“So my baby won’t nap longer than 45 minutes and he has started waking every 2 hours overnight…..I am exhausted! And so are they!”

Sound familiar? Read on…

The Four Month Sleep Regression

This is not a reality for all babies but for those families who experience it, this new sleep pattern can be exhausting and confusing. Babies that had been sleeping 4-6 hours at night and napping well during the day may begin napping only 45 minutes and waking every 2-4 hours overnight.

This sleep regression can actually occur anywhere between four and six months of age and more frequently affects babes that have been chronic cat-nappers thus far (meaning they nap 45 minutes or less) and haven’t yet learned the art of re-settling themselves to sleep after they wake.

Re-settling is an important skill to learn for two reasons: 1) Babies wake partially (or sometimes fully) between sleep cycles. Adults also wake partially between sleep cycles but we are so skilled at putting ourselves back to sleep that we rarely even remember waking. When babes haven’t learned how to re-settle themselves they often wake fully and cry out, needing their care givers help in order to return to sleep. 2) Babies spend more time in a light sleep state than adults and are awakened easily when in this light state of their sleep cycle. Again, if they haven’t learned how to re-settle and are awakened from sleep, they require help from the care-giver to fall back asleep.

Baby sleep cycles during the day are 45 minutes which is why we tend to see them waking at this point. While a 45 minute nap would have sufficed while your baby was in the newborn stage, it is no longer restorative enough for your growing baby. During the night your baby’s sleep cycles are changing and maturing with partial wakings occurring every 2-4 hours.

The sleep regression is essentially 1) a cycle of over-tiredness from lack of daytime sleep, and 2) your baby needing help re-settling to sleep after partially waking between sleep cycles.

So how do we deal??

The first step is adopting a gentle nap routine. Ideally a good daytime sleep goal is 3.5 hours divided into two longer naps (one in the morning and one in the afternoon) and one short nap occurring in the late afternoon. Your baby should be able to stay awake for approximately 2 hours between naps.

If your baby is very overtired you may want to get on top of the over-tiredness by using assisted naps for 2-3 days. Assisted naps are just how they sound: naps that you help your baby achieve (i.e. wearing them in the front pack, holding them for their naps, stroller rides etc). Try using assisted naps for all three naps of the day (with approx. 2 hours in between sleeps) for a few days before attempting naps in their crib. When babies are rested they achieve sleep easier.

You also want to ensure their sleep environment is consistent and dark. For those families that are juggling other children’s school drop offs and activities try to get at least 1 out of three naps at home. Sleep environment and nap consistency become essential now as your baby’s circadian rhythm has developed. Motionless sleep (i.e. occurring in their crib instead of in a swing) is more restorative now as your baby ages. Think of the difference in rest you experience after sleeping in a car vs your bed!

Circadian rhythm is like an internal body clock that tells our bodies when to sleep, wake and eat.

Our circadian rhythm is entrained (or set) by environmental light, food, and social interaction; this is why routine and sleep environment are now so important in building and maintaining healthy sleep habits.

What does a dark environment have to do with it? A dark environment will help your baby’s body produce melatonin (the sleep hormone) which helps your baby fall asleep and stay asleep. Melatonin production is blocked in response to light and produced in response to a dark environment.

I still recommend white noise at this age for two reasons. It is soothing for babes as it replicates the whooshing sound they were used to hearing in the womb, and it blocks out external noises in their environment that may wake them while in a lighter sleep state.

"So what do I do if my baby wakes after a 45 minute nap?"

When you hear your baby stir, listen to them: are they just fussing or chatting? Or are they actually crying out in need of help re-settling? If they sound like they are just grizzling, give them a moment or two and see if they settle back to sleep. If they begin to cry, tend to them and see if you can re-settle them back to sleep (by rocking, patting etc) in order to extend their nap for another half hour/hour or so. If we automatically get them up after 45 minutes without giving it a go to re-settle them back to sleep it can reinforce the behavior of waking after 45 minutes. After you see progress in extending naps you can gradually back off the amount of assistance you are giving your baby to fall asleep.

The other important aspect of working through this sleep regression is working on letting your baby learn how to re-settle themselves and self soothe.

Babies usually begin to “find their hands” around the four month mark. Once this happens (and if you are still swaddling your baby) you may want to try swaddling them with one arm out. This way they still get the benefits of swaddling (see my previous post) but also can begin to self soothe by sucking their hand.

If you have been assisting your baby to sleep this far (ie by rocking, feeding, holding) try to gradually back off the amount of assistance you give them to fall asleep. For example try rocking your baby until they are very drowsy but not fully asleep. Then put them in their crib and see if they can finish off the job of falling asleep on their own. This can be a very gradual process or can take place over a period of days depending on your parental intuition and the response of your baby.

What else can you expect for your 4/5 month old's sleep?

- 3 naps during the day (morning, afternoon, and a short late afternoon nap)

- an awake period of about 2 hours between sleeps

- able to sleep 6 hours straight overnight with 1 or 2 night feeds (depending on weight gain)

- you may notice they are in a state of deep sleep around 7-11 pm and in a lighter sleep the rest of night where they may awaken more easily

If you are of the sleep training camp, 4/5 months is actually a nice time to begin. If your baby has any sleep associations they aren't as ingrained or strong at this age compared to older babies which can make the sleep training process easier. For this wee age group we do modify sleep training techniques in order to match their developmental age. If you are finding you need help navigating this sleep regression feel free to contact me for your in- depth sleep assessment where we consider sleep environment, nutrition, nap timing, routine, and a customized sleep training plan to get your days and nights back on track!


Sara Davis (Certified Infant & Child Sleep Consultant, BSN, RN)


Anders, T.F., Halpern, L.F., & Hua, J. (1992). “Sleeping through the night: a developmental perspective”. Pediatrics 90(4): 554-560

Weissbluth, M. (2003). Healthy Sleep Habits, Happy Child.

Goodlin-Jones, B.L., Burnham, E, Gaylor, E & Anders, T.F. (2001). “Night waking, sleep-wake organization, and self-soothing in the first year of life”. J. Dev Behav Pediatrics 22(4): 226-233.

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