Research About Baby and Toddler Sleep
Baby sleep not only leaves parents often baffled, but researchers are trying to unveil the hidden secrets as well
Nothing seems ordinary when it comes to baby sleep. Our little ones will always come up with something new, don't they? Anything, you just name it. One day they like to be rocked, the other day, they will shove away your hand because how dare you touch them.
They will sleep through the night one day, and then you do the exact same thing the next day, but this time you have to handle one night waking after another.
Seems all logical, right? HA HA HA
So I would always say to a new parent: baby sleep is extraordinary. Extraordinarily tiring and extraordinary weird. You just gotta love it!
Well, not only do we mamas often wonder...what the heck?! Also, the world of science is taking an eager interest and trying to learn more about baby and toddler sleep. Maybe someday, we will unveil it all.
So here, I have collected some interesting studies that talk about different sleep related issues. Of course, there is always space to argue. Science has given us great advances in understanding baby sleep. But please keep in mind that research findings always depend on the implementation and may be limited. You will find all references to the literature, so feel free to read it in more detail there.
6 Years of Disrupted Sleep for Mothers and Fathers
Richter, D., Krämer, M.D., Tang, N.K.Y., Montgomery-Downs, H.E., & Lemola, S. (in press/2019). Long-term effects of pregnancy and childbirth on sleep satisfaction and duration of first-time and experienced mothers and fathers.
A research team at the University of Warwick studied the sleep duration and sleep satisfaction of overall 4659 parents who had children born between 2008 and 2015. Parents thereby reported on their sleep in interviews. And the results showed that after 6 years, parents' sleep duration was still shorter than before having kids. The study even revealed that the sleep changes were more pronounced in first-time parents than in experienced parents.
Wait what?! Does this confirm your worst fear? Will I EVER sleep again?
Yes, you will sleep but differently. I'm sorry to tell you, but your sleep will probably never be the same again. There is no such thing as consistent sleep when it comes to kids, especially during early childhood. Not only have babies completely sleep pattern than adults, which first need to evolve, but your mom instinct antennas will work now 24/7, forever. It doesn't matter if your baby is sleeping soundly or not.
But incredibly, your body and mind will cope with it. And once your little one sleeps completely through the night, you will have restful and healthy sleep, even if you snooze with one eye open and one ear listening.
Mom’s Voice Wakes the Baby
Four-month-old infants process own mother's voice faster than unfamiliar voices--electrical signs of sensitization in infant brain, Purhonen M, Kilpeläinen-Lees R, Valkonen-Korhonen M, Karhu J, Lehtonen J, Brain Res Cogn Brain Res. 2005
There have already been several research stating that infants not only recognize their mother's voice early on, but it also activates specific regions of the brain. A study conducted with 4-month old babies showed that they processed the mother's voice faster than other voices. They are also more aroused by it.
When we look at these results with regard to baby sleep, it seems logical that you will often read about advice to minimize interaction with your baby during the night. Too many disruptions during the night will not only wake your little one, but your voice has an additional power to arouse your baby from their sleep.
A Wet Diaper May Not Bother Your Baby
Do wet diapers induce arousals in sleeping infants? Zotter H, Urlesberger B, Pichler G, Mueller W, Kerbl R. Acta Paediatr 2007
Heinz Zotter from the Medical University of Graz conducted an experiment with his team to find out if a wet diaper causes infants to wake up. Thereby, they simulated a baby peeing by adding water into the diapers of 34 infants. Their result was that the wet diaper neither caused any awakening nor did it induce any body movement in the sleeping infants.
So your little one might not be bothered by a wet diaper, and a diaper change can actually arouse your baby from their sleep.
Now, of course, if your little one's diaper is soaking full or the baby poops during the night, you should definitely change their diaper. At around 3-4 months, most babies stop pooping at night. Then you can also reduce nightly diaper changes. Depending on the amount of milk your baby drinks during the night, one diaper change might be enough for up to 6 months. After that, many babies don't even need a diaper change anymore. If your baby is back asleep after a feeding, there is also no need to change a wet diaper.
Baby Sleep Is Influenced by the Wellbeing of the Mother During Pregnancy
Profiles and Predictors of Infant Sleep Problems Across the First Year, F Cook, L Conway, D Gartland, R Giallo, Journal of Developmental and Behavioral Pediatrics 2019
A research study conducted by the Murdoch Children's Research Institute with 1460 pregnant women found that mothers who had poor mental and physical health during their pregnancy are more likely to have babies with sleeping problems. Their study suggests that babies are predisposed to sleep resistance which can cause a sleep problem as a baby.
This research only highlights how important it is for mothers-to-be to take good care of themselves. Knowing that prenatal health factors can play an important role when it comes to baby sleep, it is even more crucial to avoid stress factors, reduce work when possible, and look after your body.
Parents Don’t Want to Admit They Are Co-Sleeping
Stewart, S: Co-Sleeping: Parents, Children, and Musical Beds, 2017
Dr. Susan Stewart, a professor of sociology at Iowa State University, discovered that 50% of parents who co-sleep kept it a secret from friends, family, and their pediatrician. She interviewed 51 parents that stated that due to fear of being judged, they do not admit that they are bed sharing with their child.
Doctors and health care providers mostly advise against co-sleeping with a baby in the same sleep space due to the risks of SIDS (sudden infant death syndrome) and suffocation. But co-sleeping or bed sharing is natural in many cultures and can be practiced safely.
Choosing a sleep arrangement is a very personal choice. It is actually quite sad that due to pressure, many parents feel the need to give up co-sleeping or think they should hide it.
Whenever you are bed sharing, please make sure to create a safe sleep environment for your baby.
Avoid Late Naps
Daytime nap controls toddlers' nighttime sleep, Nakagawa M, Ohta H, Nagaoki Y, Shimabukuro R, Asaka Y, Takahashi N, Nakazawa T, Kaneshi Y, Morioka K, Oishi Y, Azami Y, Ikeuchi M, Takahashi M, Hirata M, Ozawa M, Cho K, Kusakawa I, Yoda H., Sci Rep. 2016
In this study, 50 toddlers with an average age of one and a half years were monitored for 7 consecutive days. Thereby, they wanted to analyze the correlation between nap duration and nighttime sleep duration as well as sleep onset time. The results of the study suggest that late naps postponed the drowsiness of the babies and led to a later bedtime. They also had a harder time falling asleep.
While it is more important how much your baby sleeps overall in 24 hours, naps at the right time and with the proper length can lead to better nighttime sleep. The longer your little one sleeps during the day, the less they will sleep at night.
Also, the last wake window between bedtime and last nap is often the most crucial. So if you are aiming for a consistent bedtime, afternoon naps should only be short, and the last wake window should ideally be the longest. I don't know any parent who did not dread their child falling asleep in the car at 4 PM.
Of course, there is always room to argue when it comes to research. How accurate is it? How big were the focus groups? And can the results be applied to all children? Probably not, but it is definitely worth knowing what has been studied so far!