Baby Sleep Regressions: What They Are and When They Happen

The AAP’s guidance for parents puts it in one line: babies do not have regular sleep cycles until about 4 months of age. Newborns sleep about 16 to 17 hours a day, it says, but may only sleep 1 or 2 hours at a time.

Sleep research describes how that structure forms. A 2016 paper on scoring sleep in babies up to 2 months old notes that sleep onsets are more often REM sleep until 2 to 3 months after term. A 2026 review of sleep in the first year describes the dominant sleep state shifting from active sleep in newborns to non-REM sleep at 12 months, with night sleep consolidating and fewer night wakings over the year.

The month-by-month data point the same way. In a study of 75 typically developing infants, parents kept sleep diaries for 6 days each month for a year. The largest increase in self-regulated night sleep came between 1 and 4 months, and the authors concluded that the most rapid consolidation in infant sleep regulation happens in the first 4 months. The research describes this period as rapid consolidation, not a decline.

The AAP’s advice for babies 4 months and older is to put babies to bed drowsy rather than waiting until they are asleep, so they learn to fall asleep on their own in their own bed. Babies who are held or rocked to sleep, it says, may struggle to go back to sleep if they wake up during the night.

The AAP also says it is normal for a 6-month-old to wake during the night and go back to sleep after a few minutes, and that you can still attend to them if needed, for example to feed them, change a dirty diaper or comfort them if they are sick.

The later ages do not appear in the AAP, NHS or MedlinePlus pages behind this guide. Those pages name causes rather than ages. The NHS says growth spurts, teething and illnesses can all affect how your baby sleeps, and that teething discomfort or hunger may wake some babies during the night. MedlinePlus says bedtime habits can be disrupted by changes or stresses, such as moving to a new home or gaining a new brother or sister.

Separation anxiety is one cause the sources tie directly to bedtime. MedlinePlus says a baby may cry when laid in bed because they fear being away from you. An AAP page on development at 8 to 12 months describes a baby who refuses to leave you to go to sleep and may wake up searching for you in the night. Our guide to separation anxiety covers that milestone in full.

If bedtime protest in a toddler looks like plain tantrum, our tantrums guide covers the response. For what the research says about growth spurts and sleep, see our guide to baby growth spurts.

Set against the ages you will see named elsewhere, this is what the official pages behind this guide say:

None of the AAP, NHS or MedlinePlus pages behind this guide gives a length, because none of them describes a regression in the first place. The figures quoted elsewhere differ from site to site, which is what you would expect of estimates.

What the research does show is that night waking is normal and becomes less frequent with age. A 2012 systematic review of 34 studies found reported night waking ranging from 0 to 3.4 times a night in babies up to 2 months old, and from 0 to 2.5 times a night in 1 to 2 year olds. A study of 226 families that measured sleep at 3, 6, 12 and 18 months found night wakings declined from 3 to 18 months with all three methods it used.

If your baby is having problems sleeping, the NHS advice is to speak to your health visitor. Outside the UK, ask your baby’s doctor.

The sources agree on routine. MedlinePlus advises making the bedtime routine consistent and pleasant, putting your child in bed before they are deeply asleep, and keeping night feeds dark, quiet and low-key. The NHS suggests a simple, soothing bedtime routine, and also says to be prepared to change routines as your baby grows and enters different stages. The AAP adds, from 4 months, not to rush in to soothe a crying baby, because babies need time to put themselves back to sleep.

Whatever is behind a broken night, the AAP’s rule is unchanged: every sleep on the back until 1 year of age. Our safe sleep guide has the rest of the rules. If you want a reference point for awake time during the day, our wake windows calculator lists typical ranges by age; the official pages behind this guide give total sleep by age, not awake times.

Growbaby can help with the record-keeping: sleep is one of its ten one-tap trackers, and its adaptive soothing detects crying on the device and adjusts a live soundscape in response. It is not the only app that responds to crying, and our comparison of apps that start a sound on a cry is honest about where it is not the best pick.