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The Nine-ish Month Sleep Regression: What is it and what can be done about it?

The Nine-ish Month Sleep Regression: What is it and what can be done about it?

Every time you think have your baby’s sleep figured out, it will change. Most of this change is positive, with sleep gradually improving with age, but there are a few notable bumps in the road that can cause trouble. One of these is the “9-(ish) Month Sleep Regression”, dubbed so by us because it can happen anywhere between 8-12 months. For most babies, it hits right around the 9-month mark. This sleep regression is different than the four-month sleep regression, where the architecture of sleep itself was changing and maturing. This sleep regression is associated with developmental milestones.

When babies have a true regression, things may get better after a rough week or two, or you may find yourself stuck in a bad pattern that will only get better with intervention. The key to getting back on track quickly after a regression depends on how you interact with your baby during this tricky time.

The Science

Right around the 9-month mark babies go through an explosion of development. It’s often the time that separation anxiety hits and it’s also a time when babies tend to get more verbal and physical. Each of these cognitive and physical milestones can cause sleep disruption, but when they coincide, your baby’s sleep habits may abruptly change (see motor skill milestones blog here). When your baby starts to experience separation anxiety, it means that she understands that when you leave the room you are still around, but not immediately available. Most babies would prefer to have their parents nearby all of the time when going through this phase of development.

It’s important to note that not every baby will go through this separation anxiety-related sleep regression and some babies don’t have very severe separation anxiety. Typically the stronger the separation anxiety, the more pronounced the reaction you will get when you try to leave your child’s room at bedtime or nap time.


Need More Help?

We offer several options for optimizing your child's sleep:

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

PHONE CONSULTATIONS (with one of our sleep experts)

THE SECRET TO NAPS (downloadable e-book)


How do I know if my baby is going through separation anxiety?

How do I know if my baby is going through separation anxiety?

The easiest test of whether separation anxiety is likely the cause of your baby’s sleep disruption is to assess her response when you walk out of the room while she is playing during the day. If she was content playing on her own when you were in the room but cries when you leave the room, then she is probably going through this phase.

What happens to sleep during this time?

What happens to sleep during the 9 month sleep regression?

If your typical bed/naptime routine involves you leaving the room, so your child can fall asleep independently, you may find that all of a sudden she starts crying as soon as you leave. This crying may sound different than the “working-through-the-day” type of fussiness that many babies exhibit at bedtime. This type of crying is more like “HEY! Where are you going!?” If you don’t know that this regression is coming, then you will probably go back into the room to investigate the problem. You might wonder if your baby is getting sick or teething or you might blame the crying on poor naps. To help your baby calm down, you might rock or nurse your baby to sleep even if that isn’t your normal process. If your baby usually sleeps through the night, you may hear from her in the middle of the night and she may stay awake for a while. If your baby wakes to eat at night, then during this regression you may hear from her at times when you know she wouldn’t be hungry.

Naps can also be affected by this regression. You may find that your baby begins to cry hard when you leave the room at nap time. You may also find that she regresses from nice long 1.5-hour naps to 30-45 minute single sleep cycle naps.

What can be done about this regression?

Unlike the four-month regression, this is a regression that you have to wait out. It is a true regression and sleep should improve as your baby starts to understand that you are available to her even when you are out of sight. That said, it is possible to create new sleep associations when responding to your baby during the regression. If your baby develops new habits as a result of the regression, then you will need to do some intervention to teach her to fall asleep on her own again.

If your baby has not yet gone through this regression and is currently sleeping well:

If your baby hasn’t gone through this regression yet, just watch for the changes described above. If she starts to cry hard as you leave the room, test the waters a bit by going in the room, repeating the end of your bedtime routine, and leaving again to see if this does the trick. If your baby is still having a lot of trouble going to sleep on her own and separation anxiety seems relatively mild, then go back to the sleep intervention you used when you taught your baby to sleep independently the first time, and she should remember what to do. Remember, your sleep training strategy (whether very interactive or more hands-off) was your way of letting your baby know that you would be available if she had a problem and was a way to cue her to sleep. By going back to those familiar cues, she will understand that you are asking her to go to sleep and will be reassured that your leaving is not a problem. If separation anxiety seems moderate to severe, you may want to switch to a more interactive, in-room type of sleep training strategy (if you have not done so before) so that leaving the room frequently with an out-of-room or check-in scheme does not exacerbate separation anxiety. Camping Out is a strategy that has been shown to be a better option during this phase of separation anxiety. Our sleep training class offers a version of Camping Out and other interactive sleep training approaches.

If you created a new parent-led sleep association in response to this regression:

If you inadvertently created a new sleep association (like rocking or feeding to sleep) in reaction to your baby’s regression, you can go back to your sleep intervention of choice. As above, if you did a sleep intervention, using the same steps should help remind your baby that what is happening is not a problem scenario. Also as above, if separation anxiety is moderate to severe – you might consider a more interactive style approach this time around.

If you have never done sleep training to change parent-led sleep associations:

If your baby has always had a sleep association (see our posts on the four-month regression for what sleep association waking looks like), consider waiting until your baby is out of this phase before beginning an intervention. Fixing a sleep association involves weaning your baby off of actions that you do to help your baby sleep. Given that this involves creating separation at some point, it’s often difficult for babies with strong separation anxiety to adjust to that type of change. If you can’t wait to start sleep training, due to your schedule or mounting sleep deprivation, consider using a sleep intervention that involves staying entirely in the room with your baby or being mostly out of the room (again, our class offers these types of options). At this age going in and out of the room (i.e., checking in or graduated extinction) doesn't work as well, because coming in and out of the room involves repeating the experience that your child finds most stressful (i.e., you leaving the room) over and over.

What should be done to get naps back on track?

If your child is having trouble falling asleep but stays asleep for a reasonable amount of time, then you don't necessarily need to change anything unless the way you are putting your child down is a problem for you. If your child is having trouble falling asleep at nap time and having short naps, then you will probably need to do some sort of nap training to get back on track. Our nap troubleshooting blogs and e-book should help you figure out what to do.

What if your child is still having trouble after making these tweaks?

It is possible to implement other strategies, including taking things slow and steady, but what you do depends entirely on your individual situation. If you need help figuring out what to do, consider booking a sleep consultation with us to develop a plan.


DeLeon, C.W. and Karraker, K.H., 2007. Intrinsic and extrinsic factors associated with night waking in 9-month-old infants. Infant behavior and Development, 30(4), pp.596-605.

Kahn, M., Juda-Hanael, M., Livne-Karp, E., Tikotzky, L., Anders, T.F. and Sadeh, A., 2019. Behavioral interventions for pediatric insomnia: One treatment may not fit all. Sleep.

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