Sleep regression in babies: What causes it and when does it happen?

Sleep regression in babies: What causes it and when does it happen?

The term "sleep regression" refers to a period when babies suddenly don’t sleep as well as they had been previously, wake up more often or suddenly refuse to take a nap. Sleep regressions usually occur several times in the first two years of a child’s life, with parents typically observing them around 4, 8, 12, 18, and 24 months.

But why do sleep regressions occur more at these stages and what causes them? And what can you as a parent do to help your baby sleep through the night again? In this article, we’ll give you all the helpful information you need on the topic of baby sleep regressions and toddler sleep regressions.


When do sleep regressions occur?

A sleep regression is a period in which a baby's sleep behaviour reverts to an earlier development stage; symptoms can range from increased crying during sleep and to more difficulty falling asleep. The various sleep regressions babies can experience are generally believed to be linked to the different growth spurts that babies go through in their early years.

Babies learn new motor and cognitive skills during their growth spurts. Growth spurts tend to occur at similar times in babies' development, but they don't follow a regular or set schedule. So, there’s no reason to worry if your baby starts crawling a little later, for example.

Babies process newly learned information while they sleep and store it in their long-term memory. This is just one of the reasons why sleep is so important for babies. Babies often try to repeat and practise newly-learned movements during sleep. For this reason, their sleep becomes more restless, they move more and wake up more frequently. Their brains are particularly active at this time and it's harder for them to relax and sleep through the night.


What exactly happens during sleep regressions?

As previously mentioned, the brain goes through some changes at the start of a growth spurt. For most babies, the growth spurt in the fourth month involves a particularly large number of mental and physiological changes, as this is when the brain matures very quickly. This sometimes results in babies’ having to relearn how best to sleep at night. Though sleep regressions might be very stressful for you as a parent, they are actually a positive sign that your baby is developing normally and healthily.

The sleep regression at 4 months

In the first few months of your baby’s life, it's a small milestone when they sleep through the night for several hours at a time. Some babies can even sleep for up to 5 hours without waking up. This can change quickly in the fourth month, however, because this is when the first growth spurt begins.

Signs that your baby is going through the sleep regression at four months include frequent and increased fussiness, frequent sleep interruptions, shorter nap duration and increased appetite. These affect not only the child's behaviour, but also their sleep phases. As is the case with adults, babies have REM and non-REM sleep phases that they go through several times per night.

Babies stay in the dream phase much longer than adults and only wake up more often in their lighter sleep phase. Whereas the dream phase accounts for about 20 to 25% of an adult’s sleep, this phase is nearly twice as long in babies. In the fourth month, their sleep phases change, with the deep sleep phases gradually becoming longer. This is unfamiliar for babies at first, so they might wake up and cry as they transition from one sleep phase to the next.

The motor changes that become notable in the fourth month include grasping after objects and the so-called oral phase, during which many babies try to put objects in their mouths. Some babies also start to roll over at this stage and may even be able to roll over onto their tummies on their own. During the night, these exercises are repeated, so your baby might move more during sleep than before.

The sleep regression at 9 months

At this stage, seven to nine-month-old babies are mainly refining their gross motor skills. Babies learn how to move around by scuttling or crawling and pull themselves up on furniture to stand up.

In addition, new learning processes are also taking place in the brain: Babies learn to distinguish between objects and people and to recognise certain sequences and patterns in the daily routine. This is where babies' daytime naps may become shorter and their nights more restless, as they want to practise as much as possible.

The sleep regression at 12 months

In the twelfth month, many babies learn to walk; some are able to already. There is also another big change in that babies start teething at around this time. Once more, babies may refuse to lie down at naptime or become more restless and fussy.

Many parents think that their baby suddenly only needs a nap once a day. The reason for this could be the sleep regression and this is only temporary. Most babies don't need only one nap a day until they are 15 months old.

The sleep regression at 18 months

As babies get older, their sleep also becomes more regular. However, this sometimes changes again at around eighteen months, when some babies go through yet another sleep regression. In the eighteenth month, children are increasingly able to consciously perceive their environment, which is of course particularly stimulating or exciting for them.

At around this age, toddlers also usually start to learn to occupy themselves independently and to distinguish wrong from right. The growing independence is accompanied by a stronger will and many toddlers refuse to lie down in the evening or take a nap.


How long does a typical sleep regression period last?

Sleep regressions can last about 2 to 6 weeks in babies and toddlers. It’s important to keep in mind that every child sleeps differently. Some can go back to sleeping well after a few days, while others may take a little longer.


What can I do about sleep regressions?

For babies and toddlers, a repetitive routine is best because it helps them fall asleep faster in the evening. You can also get your child used to certain bedtime rituals to help them get to fall asleep faster in the evening. We recommend using a sleep log to keep track of your baby's wake up and bedtime schedule. This will help you notice changes in your baby's sleeping habits more quickly and keep track of the times when your child usually starts to get tired.


Better sleep with Zizzz products

At Zizzz, we have some great products to help babies and their parents get a good night’s sleep. For an optimal sleeping climate and your child’s safety, we recommend the use of our baby sleeping bags. Our four seasons sleeping bags can be used year round, while our special summer sleeping bags are best for the warmest summer nights.

Our snuggle toys are a great choice to keep your child company at night. These are made from purely natural materials, namely organic cotton and Swisswool, so you don’t have to worry about the use of pesticides or other chemicals. These cuddle cloths are perfect for babies who want to practice their fine motor skills and grasping reflexes.

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