The Toddler (16-18-ish) Month Regression: What is it and what can be done about it?

The Toddler (16-18-ish) Month Regression

When it comes to sleep, the graduation from “baby” sleep to “toddler” sleep usually happens around 18 months. This transition involves a subtle biological change associated with the transition to one nap, but the sleep regression that many toddlers experience is caused by an explosion of cognitive and emotional development. We call this the 18-ish month sleep regression because it can happen anywhere between 15-24 months. For most toddlers, it hits right around the 18-month mark. Your toddler might have a true regression and get better with minimal effort after a rough week or two or he might get stuck in a bad pattern that will only get better with intervention. The key to getting back on track quickly depends on how you interact with your child during what can be a tricky time.


Need More Help?

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SLEEP TRAINING CLASS (for well babies 6-15 months)

PHONE CONSULTATIONS (with one of our sleep experts)

THE SECRET TO NAPS (downloadable e-book)


The Science Behind the 16-18 Month Regression

Right around the 18-month mark toddlers go through an explosion in development. The transition to one nap has usually happened by this time (see our nap blogs) and making it through the day on just one nap can be a tough transition. In addition, recent research has shown that the biological bedtime conferred by the circadian rhythm drifts by as much as an hour later during toddlerhood. (In other words, that same tried and true baby bedtime you’ve had for months stops working!). This circadian rhythm shift is problematic because the strongest drive to be awake happens right before the biological bedtime. The practical consequence of this is that you can end up with a toddler, who is obviously tired from having just one nap, but who cannot sleep at bedtime.

It gets worse. Now, biologically you have a tired child who cannot sleep, so what’s an overtired toddler to do with all that extra time? Unfortunately, this age is also when testing behavior happens and it’s also a time when a second separation anxiety can hit with a fury (see our blog on the first separation anxiety regression at 9 months. Some children will fill their extra awake time with experimentation that many parents interpret as active manipulation, but it’s really more just figuring out limits and consequences – What happens if I yell? Can I get out of this crib? Jumping is fun! How long can I jump? What happens when I sign/ask for milk? What happens when I sign/ask for a snack? What happens when I sign/ask for the stroller? Is it nice to sleep on the floor? Can I sleep in my parents’ bed?

On the other hand, with moderate to severe separation anxiety, some children develop genuine but sometimes irrational, fears – Where is my mom going? What if she doesn’t come back? What if I need her and she doesn’t come? What is that shadow? A dog barked at me today and it was scary. What if a dog comes in my room?

Since natural wakings happen throughout the night at the end of every sleep cycle, these problems can repeat themselves for hours in the middle of the night. This can be even more challenging for children who have not yet developed strong language skills (most haven’t at this age) because it’s hard to know whether cries should be interpreted as “I want that toy” or “I’m worried”.

Some children can experience elements of both of these issues, making it even more difficult to figure out how to respond appropriately.

What do I do about this regression?

Avoid making big sleep changes during this time.

Sometimes you can’t avoid life changes, like moving or the arrival of a sibling, but if your child has sleep issues or if you want to make a change in your child’s sleep experience, then it’s best to try to make those changes before the 18-month mark or wait until this volatile period is over (e.g. sleep location transitions, pacifier weaning etc). We know that sometimes you just can’t wait, but for those situations we recommend considering booking a consultation with us so that we can evaluate your child’s individual needs.

Provide your child with consistency and clear limits.

If your bedtime routine changes every day or doesn’t have a defined end, then it will be tough to convince your child that there is a reason to stop reading books, singing songs, or otherwise engaging with you. Intermittent “giving in” is actually very reinforcing (think gambling), so negotiating with your child (e.g. if I read you one more book, then you have to promise to go to bed) can actually backfire in the long run. It can be really helpful to use a bedtime checklist with pictures or to glue pictures of the steps in your routine on cards that your child can put in an envelope when each step is complete. Once the end of the routine happens, you should not give in with more books, snacks or activities. The end should be the end. This doesn’t mean that your routine cannot involve you being in the room with your child, but even if you stay in the room, you can and should expect that your child follows the “sleep rules” at the end of the routine.