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Baby sleep regression tracker & calculator

Find out which window your baby is in — and what's coming next

Sleep regressions most often show up around 4 months and sometimes 6 months, 8–10 months, 12 months, 18 months and 2 years. Enter your baby's birth date to see which one they're in now, or which one is coming up next.

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  • Covers 4 months to 2 years
  • Adjusts for prematurity
  • Free, no sign-up to start
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Track your baby's sleep regressions

Enter your baby's birth date. We'll show you which regression window your baby is in today.

Add a birth date to see the windows.

What is a sleep regression?

A sleep regression is a stretch of days or weeks when a baby who had been sleeping predictably suddenly starts waking more at night, fighting naps, or taking a long time to settle — without being ill. It usually lines up with a developmental leap, a shift in how much sleep your baby actually needs, or a change in routine.

It's worth being honest about the evidence. The 4-month window is the one with real physiological backing: sleep cycles mature permanently at around that age, which is why sleep so rarely returns to how it was on its own. The later windows — 6, 8–10, 12, 18 and 24 months — are patterns parents report consistently and that line up neatly with known developmental milestones, but they aren't established stages in the research literature. Treat them as a weather forecast, not a timetable.

Individual babies vary by several weeks in either direction, and a baby born prematurely will track their corrected age rather than their birth date. That's why this tracker asks for a due date if your baby arrived early.

Sleep regression ages and stages chart

Every commonly reported window, what drives it, how long it typically lasts, and how much evidence sits behind it.

  • 4 months (can start at 3 months or run into 5 months)

    Strong

    Waking every 45 minutes to 2 hours all night long. Rolling and settling in the crib.

    Typical length · 2–6 weeks

  • 6 months (some babies feel it closer to 7)

    Limited

    Sitting or rolling in the crib instead of settling. Sitting up and lying back down.

    Typical length · 1–3 weeks

  • Limited

    Standing up in the crib and not knowing how to get down. Getting from standing back down to sitting.

    Typical length · 2–6 weeks

  • 12 months (can show up from 11 months)

    Limited

    Refusing the morning nap for a few days, then wanting it back. Walking and standing balance.

    Typical length · 2–4 weeks

  • 18 months (anywhere from 17 to 19 months)

    Limited

    Flat refusal to get into bed or stay there. Words for feelings, and a fixed bedtime routine.

    Typical length · 2–6 weeks

  • 24 months

    23–25 months

    Limited

    New fear of the dark or of being alone in the room. Quiet independent play and naming feelings.

    Typical length · 2–6 weeks

Is there a 3, 15 or 20 month sleep regression?

Parents often notice sleep changes at other ages too. These are the ones we're asked about most.

6 weeks

Not really a regression. A lot of babies have a growth spurt and get fussier around 6 weeks, so they feed more and sleep less for a few days, and then it settles.

Read more about 6 weeks

3 months

Some babies start the 4-month changes a few weeks early, as their sleep patterns mature and their body clock develops. You might see more night wakings and shorter naps.

Read more about 3 months

14–16 months

Yes, and it's a common one. Walking, teething, separation anxiety and early nap changes can all get in the way of sleep, sometimes for a few weeks and sometimes for a couple of months. Hold on to the second nap for as long as your toddler still needs it.

Read more about 14–16 months

20–22 months

New words, more independence and back molars coming through can all upset sleep around now. It usually lasts 2–6 weeks.

Read more about 20–22 months

2.5 and 3 years

Bedtime battles, early waking and skipped naps are common around this age. They often show up alongside big changes like potty training, a new sibling, moving to a big-kid bed or a new fear of the dark. Most of the time, things settle within 2–6 weeks.

Read more about 2.5 and 3 years

Signs of a sleep regression

A sleep regression usually starts suddenly, after a stretch of decent sleep. Look out for:

  • More night wakings, often at times your baby used to sleep through
  • Shorter naps, or refusing naps altogether
  • Taking a lot longer to settle at bedtime
  • Being fussier and clingier during the day
  • Changes in feeding, like wanting more feeds or being too distracted to feed
  • Restless sleep, with lots of tossing and turning

Is it a regression, or something else?

Plenty of bad nights get filed under "regression" when the cause is simpler — and more fixable. Before you ride one out, rule these out.

Teething

Comes in bursts of one to three days, with drooling, gum-chewing and a preference for cold things. Eases with comfort.

Illness

Arrives suddenly and usually with something else — fever, congestion, a change in appetite or diapers. Sleep returns when the illness does.

An outgrown schedule

Bedtime battles, short naps and early waking that build gradually over weeks. Usually fixed by lengthening wake windows or dropping a nap.

A change at home

A new room, a house move, starting daycare, a new sibling, a trip across time zones. Look at the calendar before looking at development.

Five things that shorten a sleep regression

  1. Keep the routine identical

    The same four or five steps, in the same order, in the same room. During a regression, predictability does more work than any single technique — your baby is looking for something that hasn't changed.

  2. Protect the sleep environment

    Dark enough that you can't read in it, steady white noise at conversational volume, and a room between 68 and 72°F. A dark room matters more once your baby is mobile and easily distracted.

  3. Watch the wake windows, not the clock

    Most regression-era wakings are really overtiredness. When a nap is short, bring the next sleep forward rather than pushing on to the usual time.

  4. Practice the new skill in daylight

    Rolling, sitting, pulling up, walking — a brain rehearsing a new motor skill will rehearse it at 2am. Ten minutes of floor practice, twice a day, gets it out of the system faster.

  5. Comfort without adding a new prop

    Respond, absolutely. But a new habit introduced in week one of a regression is usually still there in week eight, long after the developmental leap has finished.

Built for the 4-month window

A crib that responds before your baby fully wakes

The hardest part of a regression is the moment your baby surfaces into light sleep and needs help getting back down. Cradlewise picks up early wake-up signs and starts bouncing automatically — often before anyone is properly awake. The built-in monitor and sleep tracking show you exactly how the nights are changing, which is how you tell a regression from a schedule that has stopped fitting.

Explore the Smart CribRead the sleep guides
Baby sleeping in the Cradlewise Smart Crib

Frequently Asked Questions
About Sleep Regressions

How accurate is a sleep regression tracker?
It is a guide, not a diagnosis. The age windows come from the ages at which developmental changes typically cluster, and individual babies vary by several weeks in either direction. The 4-month window is the most reliable because it reflects a real, permanent change in sleep architecture; the later windows are patterns parents consistently report rather than established developmental stages. Use the tracker to know what is likely coming, not to predict a specific night.
What is a sleep regression?
A sleep regression is a stretch of days or weeks when a baby who had been sleeping predictably suddenly wakes more at night, fights naps, or takes much longer to settle — without being ill. It usually lines up with a developmental leap, a change in sleep needs, or a big change in routine. Most last between one and six weeks.
At what ages do sleep regressions happen?
The commonly reported windows are around 4 months, 6 months, 8–10 months, 12 months, 18 months and 2 years. The 4-month window is the one with real physiological backing — it is when sleep cycles mature permanently. The later windows tend to track motor milestones, separation anxiety, teething, nap transitions and, in toddlers, the arrival of independence and imagination.
How many sleep regressions are there?
There's no official number. The ones parents notice most are around 4 months, 6 months, 8–10 months, 12 months, 18 months and 2 years. Some children also have smaller bumps at 15 months and around 2.5–3 years.
How long does a sleep regression last, and when does it end?
Typically two to six weeks. The 6-month window is often the shortest at one to three weeks. The 4-month change is different: the disruption settles in two to six weeks, but the underlying change in sleep cycles is permanent, which is why sleep habits often need adjusting rather than simply waiting it out. It ends once your baby has adjusted to the new skill or change, usually within 2–6 weeks.
Which sleep regression is the worst?
Many parents find the 4-month regression the hardest. Around this age, your baby's sleep cycles start to work more like an adult's. That change is permanent, so it can take a few weeks for everyone to adjust. The 18-month regression is often a close second, because toddlers can now protest bedtime loudly. Some babies barely notice either one.
Do all babies go through sleep regressions?
No. Most babies have at least one rough patch, but many skip some regressions or get through them in a few nights. The ages in our chart show when sleep is most likely to change. Your baby may not have a regression at every one.
Should I adjust the dates if my baby was born premature?
Yes. Developmental windows track corrected age, not birth date. Enter your original due date in the tracker and it will calculate from there. Most clinicians correct for prematurity until around 24 months.
Can I prevent a sleep regression?
You cannot prevent the underlying development, but you can reduce how much it costs you. Age-appropriate wake windows, a dark room, consistent white noise, an identical bedtime routine, and daytime practice of whatever new skill your baby is working on all shorten the disruption. Adding a new sleep prop mid-regression tends to extend it.
Is it a sleep regression or teething?
Teething discomfort tends to come in short bursts of one to three days, with drooling, gum-chewing and a preference for cold things, and it usually eases with comfort. A regression lasts longer, follows a pattern across both naps and nights, and often arrives alongside a new physical skill. The two frequently overlap around 6 months.
When should I speak to a doctor?
Contact your pediatrician if disrupted sleep comes with fever, poor feeding, vomiting, unusual lethargy, loud snoring or pauses in breathing, or if your baby is not gaining weight as expected. Also reach out if the disruption lasts well beyond six weeks, or if your own exhaustion is affecting your health or mood — that is a medical concern in its own right.

How this tracker works

Each window is stored as a range of days from your baby's date of birth, or from the original due date when you tell us your baby was born early. The tracker compares your baby's age in days against those ranges and marks each window as passed, happening now, approaching or upcoming. The age ranges reflect the ages at which the relevant developmental changes typically cluster — sleep cycle maturation at around four months, motor milestones and separation anxiety through the second half of the first year, and the arrival of autonomy and imagination in the second year.

This tool provides general information and is not medical advice. It cannot diagnose a sleep disorder or any other condition. Speak to your pediatrician if disrupted sleep comes with fever, poor feeding, vomiting, unusual lethargy, snoring or pauses in breathing, or if your baby is not gaining weight as expected — and equally if your own exhaustion is starting to affect your health or mood. Always follow safe sleep guidance: on the back, on a firm flat surface, in a clear crib.

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