21 Month Sleep Regression: Here’s What You Need To Know

Author Image By Paula McLaren - Norland Nurse NNEB RSH •  Updated: 08/23/23 •  Sleep / Sleep Regressions

Is your child suddenly fighting sleep? Being fussy? Struggling to settle? The 21 month sleep regression has arrived. Here’s what that means, and what exhausted parents need to know to get through it.

What Is The 21 Month Sleep Regression?

How Long Does The 21 Month Sleep Regression Last?

The 21 month sleep regression, like all sleep regressions, commonly lasts between 2 and 6 weeks depending on the trigger.

21 Month Sleep Regression Featured

21 Month Sleep Regression Signs

If you suspect your little one is experiencing a 21 month sleep regression, here are some of the signs that will confirm your suspicions:

So, if you are nodding your head in agreement whilst reading this list… Then your little one is almost certainly experiencing a sleep regression.

Looking to get your little one to sleep quickly and effortlessly through a healthy nighttime routine? Check out my Bedtime and Nap Cheat Sheet and master the art of making daytime naps and bedtimes as seamless as possible.

Causes Of The 21 Month Sleep Regression

There are a variety of causes of the 21 month old sleep regression. These are the top causes of this sleep regression that every parent should be aware of.

Causes Of The 21 Month Sleep Regression

1. They Are Reaching Big Physical, Mental And Emotional Developmental Milestones

A lot is going on developmentally at this age with your little one perfecting the art of walking, climbing and talking. There is a lot going on cognitively as well as they become increasingly aware of the world around them and their place in it.

All that extra brain and body activity can easily disrupt their sleep resulting in a 21 month sleep regression!

2. Newfound Independence

Your toddlers growing independence at this age may make them push and resist boundaries around naps and bedtimes, resulting in them becoming overtired and finding it difficult to settle and or stay asleep.

3. Their Sleep Needs Are Changing

Around this age, you may need to adjust daytime sleep, especially if newfound skills are making them more tired. If they have started daycare they may need more sleep for a while as they adjust to the new routine.

Alternatively, some 21 month olds may only need 1 long nap during the day.

4. Their Environment And Sleep Routines Have Changed

Moving house, going on holiday or visiting family overnight can all trigger a sleep regression.

And any significant changes in routine could also upset an established sleep schedule such as starting daycare, parents returning to work or the primary caregiver changing.

5. Your Toddler Is Experiencing Separation Anxiety

Separation anxiety can occur at any age and will make it difficult for your little one to fall asleep alone and to become distressed when they wake up at night and discover you’re not with them.

6. They’re Hungry

With all the increased physical activity that your 21 month old is capable of they may need more calories to keep them going. This can result in them waking more often due to hunger so you need to keep an eye on their calorie intake during the day and especially at the end of the day.

7. They’re Teething Or Unwell

Your toddler’s first molars may start to erupt at this age. If your little one is experiencing pain due to teething their sleep is very likely to be disrupted for a short while and although this is not a true sleep regression in itself, it may trigger one. Investing in a teething toy can help soothe your little one resulting in helping them sleep better!

And like teething, illness may cause a sleep disruption for a short period of time and although it’s not a true 21 month sleep regression, sickness can trigger a brief one as your little one may have become used to you responding to every cry or unsettled sleep while they were unwell.

How Much Sleep Do 21 Month Olds Need?

Your average 21 month old will need around 12 ½ hours of sleep in a 24 hour period. Most of this will be taken at night with 1 daytime nap in the afternoon lasting about 1 ½ hours long.

Tips To Get Through The 21 Month Sleep Regression

Sleep regressions are tough, there is no question about that.

However, there are things you can do to help you and your child get through the 21 month sleep regression and come out the other side with your healthy sleep habits intact.

21 Month Sleep Regression Tips

1. Stick To Your Routines

I cannot stress how maintaining a healthy daily and consistent bedtime routine will help to keep you sane and keep your little one’s healthy development on track.

It goes without saying that ensuring your little one gets consistent cues in preparation for sleep will go a long way in helping your little one fall asleep during a sleep regression. And a regular bedtime and nap routine will do just that.

I know life gets in the way sometimes, but being super vigilant about nap times, meal times and bedtimes, during a 21 month sleep regression will make your life so much easier during this time.

So, if you have to cancel a few plans over the coming weeks to ensure you’re at home for naps and bedtime, it will be worth it in the long run.

2. Get Outside Every Day

Fresh air is a great way to ensure your toddler gets some physical exercise and an opportunity to practise their new skills such as walking, running and climbing.

Fresh air also helps to stabilise their circadian rhythm (which will help to stabilise your toddler’s sleep cycles!)

3. Have Lots Of Cuddles

The 21 month sleep regression can sometimes make your little one feel less secure. Offering extra cuddles and snuggle time can help reassure them as they navigate this tricky phase.

4. Watch For Hunger Being A Nighttime Waking Trigger

It is very tempting to feed your toddler in order to get them back to sleep… however, this is not a habit you want to continue.

Try offering a healthy pre-bedtime snack such as apple slices, peanut butter, or some yoghurt before bed to help them sleep through the night.

5. Keep Nighttime Interactions Low-Key

If your little one wakes at night then it’s super important to keep your interactions low-key. Have the lights down low and do not chat to them. This will help your child to fully understand the difference between nighttime and daytime.

A night light is a great investment as it stops you from having to turn on a light when visiting them at night.

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6. Teach Your Little One To Self-Settle

If you have not done so already, try and teach your little one to self-settle. Allow them to play in their cribs or a playpen during awake times and put them down whilst drowsy and not fast asleep.

Also, try not to pick them up every time they wake.

It is very easy to fall into bad habits during a 21 month sleep regression, so if your little one is waking more at night try leaving them to fuss for a short time when they wake, as they may just fall back to sleep without you having to go to them.

If however, they start to become distressed, you should go to them.

7. Make Up For Poor Nighttime Sleep With Extra Naps During The Day

This can be a tricky phase when it comes to naps and you might be tempted to drop naps in the hope that your toddler will be more tired for bed and sleep better at night.

However, as I say over and over, less daytime sleep does NOT mean better nighttime sleep.

In fact, the complete opposite happens.

An overtired toddler is not going to go to bed peacefully or quietly.

Their bodies will be stressed and full of adrenaline…

And this is not ideal when getting ready for bed because your little one will be hyper instead.

If your toddler is transitioning from 2 naps to 1, you need to make sure that their nap is taken at a consistent time each day (preferably after lunch) and that they have had an adequately active morning to be ready for sleep.

Sometimes an extra cat nap later in the day can help your toddler get to bedtime without getting overtired.

8. Make Their Sleep Space More Conducive To Sleep

Now your little one getting older they will be more easily woken by sleep distractions and noise. So, darken the bedroom using blackout blinds and use a nightlight.

During a 21-month old sleep regression your little one needs to be sleeping in a calm, dimly lit room.

Using a white noise machine can eliminate background noise from disturbing their sleep too. They will help to ensure that sudden changes in noise will have less of an impact on your sleeping toddler.

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9. Help Your Little One Practice New Skills

It is important that you give your toddler plenty of opportunity to practice any new skills during wake times so that they are not desperate to do so when they should be sleeping.

Provide them with toys to help them walk, opportunities to learn to climb safely, play with construction toys such as building blocks and try out some simple puzzles with them too.

Read lots of books to encourage speech and cognitive development.

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Lovevery Building Block Set

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This beautiful and brilliantly designed wood block set promotes spatial, language, and problem-solving skills through bright and solid wood building blocks, planks, shapes, people, magnetic wheels and dowels with a toggle string. All are safely kept in a wooden storage box and a cotton drawstring bag for storage at the end of a busy day!

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9. Consider The Gradual Retreat Method

While I will not advocate letting your little one cry it out while experiencing a 21 month sleep regression… Trying gentle sleep training such as the gradual retreat method can often get your toddler’s sleep back onto an appropriate sleep schedule.

To learn more about my preferred sleep training method, read this: Gradual Retreat Method.

Frequently Asked Questions About The 21 Month Sleep Regression

Looking for more information about the 21 month sleep regression? Check out the most commonly asked questions here.

Why Is My 21 Month Old Suddenly Crying At Night?

If your 21 month old has been sleeping beautifully and suddenly starts waking at night this may be due to a number of triggers including teething or achieving a developmental milestone, starting day care or changing sleep needs.

While you should always rule out any illness that may be affecting your little one, if all is well then you should deal with your little one’s nighttime waking and or nap resistance as a sleep regression and follow the tips listed above.

How Will I Know When The 21 Month Sleep Regression Is Over?

When your toddler settles back into a settled sleep routine consisting of regular daytime naps and bedtime with little to no waking at night, you can safely say that the 21 month sleep regression has passed.

How Do I Look After Myself During A Sleep Regression?

As parents, we often forget to look after ourselves. Our children are our priority, and everything else falls into second place.

However, sleepless nights will undoubtedly make us short-tempered and cranky… And at the best of times, looking after a toddler requires lots of energy and patience.

So to help yourself through the 21 month sleep regression remember to:

Don’t be too harsh on yourself if you are struggling or feeling irritated from sleep challenges. Sleep disturbance and parenting go hand in hand…

But you can navigate these toddler sleep regressions if you stick to established routines, understand what is going on in your toddler’s development and hold on to the fact that this is just a phase that will pass if handled correctly.

Can I Move My Toddler Into Their Toddler Bed?

If your 21 month old is going through a sleep regression, I would wait until you’re back on track and ensure they’re getting enough hours of sleep per night BEFORE making a change to a toddler bed.

If, however, your toddler has outgrown their crib and it’s no longer safe for them to sleep in there, you will have to make the move regardless.

Is There A Developmental Leap At 21 Months?

Developmental milestones such as improved mobility, language and social skills as well as increasing desire for independence are likely to be the trigger for a sleep regression at this age.

When Do I Need To Talk To A Doctor About The 21 Month Sleep Regression?

If you are unsure if your little one’s change in sleep patterns is due to a 21 month sleep regression, watch for the following signs. If they are present then you should consult a doctor:

If your little one has a persistent fever or a cough which is waking them at night you should also consult a medical practitioner. I would also recommend seeking medical advice if your little one’s sleep issues continue for more than 6 weeks.

Why Will My 21 Month Old Not Sleep Anymore?

It is very common at this age for your little one to experience separation anxiety and will therefore find your leaving them at bedtime, nap time and coping with nighttime waking difficult.

In addition, if you have not yet taught your little one to fall asleep alone they will not like it if you have now decided that they should do so.

Overtiredness will also cause issues at bedtime and you may need to take a close look at your little one’s nap schedule and awake windows.

Further Reading

If you would like to learn more about sleep regressions and how to handle them at different ages, check out these posts:

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Author Image Bio
Paula McLaren is the founder of Teething to Tantrums and a highly qualified childcare expert with over 40 years of experience as a Norland Nanny. She holds a BA (Hons) in Early Years Development & Learning (0-6 Years) and the prestigious Norland Diploma. Paula has worked as a night nanny, run a successful daycare center in London, and helped raise countless children using her tried and tested developmental and guidance methods.

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