Download
← All guides

Baby Sleep Regressions: 4, 8 and 12 Months

By Tommy Bergeron Facts checked October 8, 2026 12 min read
sleepsleep-regressionnapsmilestonessafe-sleep

A sleep regression is the popular name for a stretch when a baby who was sleeping reasonably well starts waking more at night, fighting naps or resisting bedtime. People usually mean 4 months, 8 to 10 months or 12 months. It isn’t a medical diagnosis, and pediatric sources talk about the causes instead: sleep that matures around 3 to 4 months, new motor skills, separation anxiety, teething, illness and nap changes.

Most of these stretches pass, or turn into a new normal. This guide goes age by age, says what the evidence supports, and says where it doesn’t.

Is “sleep regression” a real thing?

The phrase isn’t in the AAP’s or the NHS’s main sleep advice. The pattern behind it is.

The children’s sleep service at Newcastle upon Tyne Hospitals, an NHS trust, describes it directly. Some babies sleep around 5 hours at a stretch by 3 months, but many start waking at night again at 4 to 5 months, and it’s normal for some to wake more often again at 8 to 9 months. Many babies keep waking through the night for at least the first year.

So the wakings are real. “Regression” is the misleading part: your baby isn’t going backwards, they’re developing fast. The NHS page on baby sleep patterns warns that sleep keeps changing as babies grow, often right after you think you’ve found a routine.

Night waking is also very common. In a Canadian study of 388 babies, Pennestri and colleagues found that 27.9% to 57.0% of 6- and 12-month-olds did not sleep through the night, depending on whether that meant 6 or 8 hours. Sleeping through the night wasn’t linked to the babies’ later mental or motor development, or to their mothers’ mood.

One caveat: a 2023 review of 93 studies on early childhood sleep architecture found far more research on the first six months than on 7 to 24 months. The later “regressions” rest on much less data.

What’s normal at each age

These ranges are for checking the big picture, not one night. For newborns and the full breakdown, see how much sleep a baby needs.

AgeTotal sleep in 24 hoursNaps and nightsSources
4 to 12 months12 to 16 hours, naps includedNight waking is still normal. A 6-month-old may wake and go back to sleep after a few minutes.AASM, AAP
6 to 12 monthsSame rangeUsually two naps a dayNHS West Yorkshire Healthier Together
1 to 2 years11 to 14 hours, naps includedYoung toddlers may still take 2 naps, which over time become 1 nap of 1 to 3 hoursAASM, NHS West Yorkshire Healthier Together
3 to 5 years10 to 13 hours, naps includedMost children stop napping by 5AASM, NHS West Yorkshire Healthier Together

The hour ranges come from the American Academy of Sleep Medicine’s consensus statement. It gives no range under 4 months, because newborn sleep varies too much and the evidence was too thin.

The 4-month sleep regression

What’s going on

Newborn sleep is built differently from ours. Young babies tend to fall asleep straight into active sleep, the newborn version of REM sleep. Over the first year, the 2023 review explains, they shift to falling asleep into quiet (non-REM) sleep, and active sleep drops from 50 to 80% of total sleep to under half. Sleep spindles, a brain-wave marker of stage 2 non-REM sleep, should be present by three months. By six months, sleep should begin with non-REM sleep.

The AAP’s page on getting your baby to sleep puts it in one line: babies don’t have regular sleep cycles until about 4 months of age.

Why more wakings? Babies wake at the end of each sleep cycle, the Newcastle service notes. A baby who fell asleep in your arms or on a feed may surface between cycles and want the same help to drift off again. NHS West Yorkshire Healthier Together says babies who learn to settle on their own are more likely to settle themselves after these natural wakings. That’s the likeliest explanation, though no source pins it on a single cause.

Other changes land around the same time. The AAP says rolling over usually happens around 3 to 4 months, and teething discomfort can start as early as 3 months, though teeth usually appear between 6 and 10 months.

What you might notice

  • More night wakings than a few weeks ago, sometimes after a run of longer stretches
  • Falling asleep in your arms and waking when you lay them down (the NHS calls this very common)
  • Harder settling at bedtime or for naps
  • Rolling in the crib, or trying to

How long it lasts

No AAP, NHS or AASM source gives a fixed length. Many sites say “2 to 6 weeks”, but we couldn’t find that figure in any pediatric source.

The research does suggest the change itself is permanent: the more mature sleep pattern is here to stay. What improves is how your baby handles the moments between cycles, and that comes with practice.

What helps

Our baby bedtime routine guide has step-by-step examples by age.

A short, predictable bedtime routine is the first thing every source mentions. The AAP says a predictable nighttime routine helps a child learn what comes next, and suggests regular bedtimes and nap times. The Newcastle service suggests a routine of about 30 minutes, such as a bath, music or a story.

From 4 months, the AAP suggests putting your baby to bed drowsy rather than waiting until they’re asleep. NHS West Yorkshire Healthier Together says the same. It won’t work every night, and it doesn’t have to.

A few other things from the Newcastle service:

  • Start the day at the same time, open the curtains and get outside in daylight. It says you may notice fewer night wakings after about 2 weeks.
  • Go to your baby before they get very upset, since a distressed baby takes longer to settle. Keep the room quiet and the lights low.
  • Move your own bedtime so you sleep during your baby’s longest stretch. If you’re splitting nights with a partner, our guide to sharing night feeds shows a few ways to do it.

Floor time while awake gives rolling somewhere to happen besides the crib (sensible, though untested). Once rolling starts, stop swaddling; see safe sleep below.

The 8 to 10 month sleep regression

This one usually stacks several things at once.

What’s going on

Crawling is one. Scher and Cohen found that babies who were already crawling had more bedtime trouble and more night waking than babies the same age who weren’t. In a later study that followed 28 babies from 5 to 11 months, the rise in disrupted sleep lined up with the start of crawling, even while overall sleep kept improving.

Separation anxiety is another. The AAP says that from the second half of the first year it can disrupt sleep for many nights, with a child waking several times and crying for one or both parents. Its 8 to 12 month development page describes a baby who won’t let you leave at bedtime and wakes looking for you at night. By 9 months, the CDC lists being shy, clingy or fearful around strangers, and reacting when you leave, as typical milestones.

Then teeth. The NHS says most babies start teething around 6 months, and teething babies may not sleep well. Naps matter too: babies from 6 to 12 months usually have two a day, according to NHS West Yorkshire Healthier Together.

What you might notice

Crying for you, often for one parent. Standing in the crib with no idea how to get down. New protest at bedtime. A nap that shrinks or disappears.

How long it lasts

The AAP says the separation anxiety stage can last several months, usually peaks between 10 and 18 months, and fades around the second birthday. The crawling research shows a temporary rise in wakings tied to the new skill, but no source gives a number of weeks.

What helps

  • Practice short separations during the day. The AAP suggests stepping out of the room at home and calling to your baby instead of rushing back, and always coming back when you said you would.
  • Keep your night response the same. The AAP says your child may need reassurance several times a night, night after night, and that a loving, consistent approach is what works.
  • If your baby pulls up in the crib and gets stuck, practice sitting back down during the day. Again, practical rather than studied.
  • Watch nap timing. A nap too close to bedtime can make settling harder, NHS West Yorkshire Healthier Together says. Our baby nap schedule by age has typical patterns.
  • No soft toys in the crib yet, however clingy your baby is. The AAP’s safe sleep advice, a fitted sheet only, applies up to 1 year.

The 12-month sleep regression

This has the least research behind it, and mostly it’s about naps.

What’s going on

Young toddlers might still take two naps, NHS West Yorkshire Healthier Together says, and over time that becomes one nap of 1 to 3 hours. The switch is rarely clean, so for a while two naps can be too many and one too few. Separation anxiety is near its peak, and by 1 year the CDC lists pulling up to stand and walking while holding furniture as typical milestones.

What you might notice: one nap refused or pushed later, a bedtime fight after a late afternoon nap, night wakings after an overtired day. Sources don’t give a duration for any of it.

What helps

  • Look at a week, not a day. One refused nap doesn’t mean your toddler is ready for one nap. A run of them might.
  • Keep naps away from bedtime, as above.
  • Try an earlier bedtime during the switch. The AAP says putting a child to bed even 15 to 20 minutes earlier can make a big difference.
  • After the first birthday, a comfort item is an option. The AAP’s toddler bedtime tips include letting your child take a favorite thing to bed, as long as it has no choking hazards.

18 months and 2 years

These get called regressions too, but the causes are more about independence. The AAP notes that many toddlers who skipped separation anxiety as babies start showing it at 15 or 18 months. NHS West Yorkshire Healthier Together adds getting out of bed, wanting autonomy and a growing imagination. Around 2, a new bed can bring a few lively nights: the AAP’s page on moving from a crib says lots of “farewell appearances” in one evening are normal at first.

The toolkit is the same: a fixed bedtime, a short routine, a comfort object, no bed sharing, and time. If your child is safe and well, the AAP suggests not going back in every time they call out, so they can learn to settle themselves.

Safe sleep, especially once your baby rolls

A run of bad nights is when exhausted parents doze off on the sofa with the baby, or bring them into bed. The NICHD’s Safe to Sleep campaign says SIDS deaths peak between 1 and 4 months, which overlaps with the 4-month regression, so it’s worth deciding ahead of time what you’ll do when you can’t stay awake.

The AAP’s safe sleep guidance for babies up to 1 year:

  • Put your baby on their back for every nap and every night.
  • Use a firm, flat surface. Nothing inclined more than 10 degrees.
  • Use a fitted sheet only. No pillows, blankets, toys or bumpers.
  • Share a room for at least the first 6 months, but not a bed.
  • If your baby falls asleep in a car seat, swing, stroller or carrier, move them to a firm, flat surface on their back as soon as you can.

On rolling, the AAP says to stop swaddling when your baby looks like they’re trying to roll over. Safe to Sleep says to stop once rolling starts, usually around 3 months, and warns that risk is very high for swaddled babies who end up on their stomachs. Keep putting your baby down on their back. Once they roll comfortably both ways, the AAP says you don’t need to keep turning them over.

When to call the doctor

Most regression nights are just hard nights. These signs are different.

  • Fever under 3 months. The AAP says to call right away for a temperature of 100.4°F (38.0°C) or higher in a baby younger than 12 weeks. The NHS uses the same 38°C line.
  • Fever in an older baby. Call if a fever lasts more than 24 hours in a child under 2, the AAP says, or right away if your child looks very ill, is unusually drowsy or very fussy, or has trouble breathing. The AAP also says teething does not cause fever, so don’t put a fever down to teeth.
  • Emergency signs. The NHS says to call 999 (or your local emergency number) if your baby is hard to wake, is breathing very fast or with difficulty (perhaps grunting), hasn’t had a wet diaper in 12 hours, or has blue, grey, pale or blotchy skin. It also lists a baby who isn’t feeding as a sign of serious illness.
  • Snoring and breathing. The AAP lists frequent snoring, breathing problems at night, daytime sleepiness and behavior problems as possible signs of sleep apnea, and says to tell your pediatrician right away. If breathing stops for more than 20 seconds, or the skin turns pale, bluish or grey, call 911.
  • No improvement. If sleep problems drag on, or your baby seems unhappy during the day too, ask your pediatrician or health visitor. The NHS points parents to a health visitor for sleep problems and routines, and its page on serious illness tells parents to trust their instincts.

Track it for a week or two

In a bad stretch, every night feels like the worst one. A simple log shows whether it’s a phase or a pattern. For a week or two, note when each sleep starts and ends, how many times your baby woke at night, and anything new: a first roll, a tooth, a cold, a dropped nap, a trip, a new caregiver. Wakings that began the week your baby started crawling and are already easing look like a phase. Wakings that keep climbing, or come with the warning signs above, are worth a call.

A log also gives your doctor real numbers instead of “they’re up all the time”. Our guide on preparing for your baby’s checkup covers what to bring.

Vivi Baby is a newborn and parents companion app for iPhone (iOS 18 or later) and Apple Watch (watchOS 26 or later). You can start and stop a sleep timer from your wrist, as the Apple Watch sleep tracker page shows. No account is needed, and the log is stored as plain files in your family’s own iCloud Drive. Logging and Trends, which shows total sleep and the longest stretch over time, are free.

Three advanced features are part of Vivi Plus ($4.99 per month or $44.99 per year, 14-day free trial). Checkups gathers growth, medical notes, recent stats and your questions before a pediatrician visit. Sleepy Time estimates the next nap and bedtime from wake windows and your baby’s own logged sleep, using rules, not AI; the baby sleep predictions page explains how. Insights spots patterns in what you log and compares them with WHO, CDC and AAP guidance, linking each source. Get Vivi Baby.

A notebook works too. Two weeks of notes tell you more than one long night, and anything that worries you is worth raising with your pediatrician.

Frequently asked questions

Is the 4-month sleep regression real?

The night waking is real, but the name is not a medical diagnosis. The AAP says babies don't have regular sleep cycles until about 4 months, and an NHS children's sleep service notes that many babies start waking at night again at 4 to 5 months. It's a change in how sleep works, not a step backwards.

How long does a sleep regression last?

No pediatric source gives a fixed length for the 4, 8 or 12 month regression, so be wary of exact week counts. The AAP says the separation anxiety behind many older-baby wakings can last several months and usually fades around the second birthday.

Do all babies have sleep regressions?

No. The NHS and AAP describe these wakings as common, not universal, and say babies' sleep varies a lot. Some babies barely change at 4 or 8 months, and that's normal too.

Can teething cause a sleep regression?

Teething can disturb sleep: the NHS lists poor sleep as a possible sign, and most babies start teething around 6 months. The AAP says teething does not cause fever, so a fever with bad nights points to illness, not teeth.

My baby rolls onto their tummy at night. Do I need to flip them back?

Always put your baby down on their back. The AAP says that once your baby can roll both ways, tummy to back and back to tummy, you don't need to turn them over, as long as the crib holds nothing but a fitted sheet.

Can I give my baby a blanket or soft toy to help with separation anxiety?

Not before the first birthday. The AAP's safe sleep advice for babies up to 1 year is a fitted sheet only, with nothing else in the crib. After 1 year, the AAP suggests a favorite comfort item at bedtime, as long as it has no choking hazards.

Sources

Vivi Baby is on the App Store

Free to download for iPhone, with a companion app for Apple Watch.

Download on theApp Store

The Vivi Babies Newsletter

Short, practical guides for tired parents, once or twice a week at most.

We never share your email with anyone else. Unsubscribe in one click, any time.