Why Newborns Wake Frequently at Night: The Biology of Infant Sleep

By Birth & Baby University · Last updated: October 2026 · 7 min read

“Is it normal that she wakes every two hours?” is perhaps the question postpartum doulas hear most after midnight. The honest answer is yes, in most cases, and the reasons are a mix of biology, feeding and development. The research behind that answer is good for some parts and thin for others, and the popular advice that a baby should be “sleeping through the night” by a certain age is not well matched to the data. This article summarizes what published reviews and studies show about newborn sleep structure, nighttime feeding and night waking, where the findings conflict, and how a doula can support families without promising a schedule.

Key takeaways

Quick answer: newborns wake often because their sleep is divided between active and quiet sleep, because they need frequent feeds, and because their sleep-wake rhythm and sustained sleep are still developing. A systematic review of observational studies found 0 to 3.4 night wakings per night in infants aged 0 to 2 months. Sleep lengthens most between birth and four months. Waking is not a sign of a problem unless it comes with illness signs, poor feeding or poor weight gain.

• The AAP describes newborn sleep as about equally divided between REM (active) and non-REM sleep, with REM sleep featuring twitching, irregular breathing and eye movement, and deep sleep from which a baby is harder to wake.
• A review of the consolidation of infants’ nocturnal sleep found the most marked changes in the first four months, especially at 1 and 2 months, and that most infants can sleep 8 hours by age 6 months and 9 or more hours afterward.
• In test-weighing data from 71 breastfeeding mothers whose babies were 1 to 6 months old, night feeds were common and made an important contribution to total milk intake.
• Studies disagree about whether feeding method changes night waking: an Australian cohort found breastfed 6-month-olds were 66% more likely to wake at night, while a survey of mothers of infants aged 6 to 12 months found no difference between breastfed and formula-fed infants.

What the research says

The structure of newborn sleep. The AAP’s page on stages of newborn sleep (last updated 2013) explains that newborn sleep is about equally divided between REM and non-REM sleep and moves through drowsiness, REM or active sleep, light sleep and deep non-REM sleep. In active sleep the baby may twitch, the eyes move under the lids and breathing is irregular. In deep sleep movement stops and the baby is harder to wake. The page describes this as the pattern of sleep stages for newborns without giving cycle lengths or numbers of normal awakenings, and it is an older, general-audience source. For the structure of newborn sleep cycles, see Understanding Newborn Sleep Cycles.

How much waking is typical. Galland and colleagues’ systematic review of 34 observational studies provided age-banded norms from questionnaires and diaries: for infants aged 0 to 2 months, a range of 0 to 3.4 night wakings per night, with mean total sleep for infants of 12.8 hours (range 9.7 to 15.9). They warned that combining data across countries and cultures means the values should be considered global norms, and that sleep was about one hour shorter in predominantly Asian-country studies. Henderson, France and Blampied’s review of consolidation found trends despite methodological differences: the greatest change in longest sustained sleep occurs in the first four months, little changes from 4 to 9 months, and a small increase follows to 12 months, and many infants can sleep 8 hours by 6 months and 9 or more thereafter. These are population averages from parent reports, so an individual baby may differ widely and still be normal.

Feeding at night. Frequent feeding is both a cause and a feature of night waking. The AAP’s page on how often a baby should eat (last updated April 2024) describes breastfed newborns as usually nursing about every 2 hours (10 to 12 sessions in 24 hours) and bottle-fed newborns every 2 to 3 hours. Kent and colleagues’ 2006 test-weighing study found that in mothers of babies aged 1 to 6 months, night breastfeeds were common and made an important contribution to total milk intake. Whether the type of milk affects waking is disputed. Galbally and colleagues (2013), in a nationally representative Australian cohort of 4,507 infants, found that after adjustment mothers of infants breastfed at 6 months reported them 66% more likely to wake at night and 72% more likely to have difficulty sleeping alone, with no association with restless sleep or problems getting to sleep, and breastfeeding was protective against wheezing, snoring and breathing problems. They suggested there may be biological reasons for night waking in breastfed infants. Brown and Harries (2015) surveyed 715 mothers of infants aged 6 to 12 months and found 78.6% of infants still regularly woke at least once a night and 61.4% received at least one milk feed, with no difference in night wakings or night feeds between currently breastfeeding and formula-feeding mothers. Infants who received more milk or solids during the day were less likely to feed at night but not less likely to wake. Both studies are based on maternal reports and neither is a trial, and they study older infants than the newborn period.

What this means for doulas

• Normalize frequent waking. For babies in the first months, waking every few hours is expected given sleep stages and feeding needs. “Sleeping through the night” is a developmental milestone that arrives gradually and varies.
• Do not promise a date. The reviews give ranges, not deadlines, and parent-reported norms overlap widely.
• Do not recommend formula or solids to improve sleep. The 6 to 12 month survey found extra daytime feeding reduced night feeding but not night waking, and for newborns, feeding decisions are for the baby’s clinician and parents.
• Protect safe sleep during night feeds. Night feeds in a sofa or bed with a tired adult are a recognized hazard. See Safe Sleep Recommendations: What Every Postpartum Doula Must Know.
• Watch for signs that waking is a symptom. Fever, vomiting, labored breathing, inconsolable crying, poor feeding or too few diapers call for the pediatric provider. See Recognizing When a Newborn Needs Medical Evaluation: Essential Red Flags for Postpartum Doulas.

Putting the evidence into practice

1. Ask for a typical night. Times of waking, feeds, diaper changes, how the parent settled the baby, and how rested the parents feel.
2. Offer simple night-feed logistics. A feeding station with water and snacks, low light, a bassinet within reach, and a plan for who handles diapers or burping.
3. Protect parents’ sleep. Offer shift-based night support, such as a block of uninterrupted sleep for each parent, because the research suggests the wakings themselves are normal.
4. Reassure with ranges. “Many babies wake several times a night in these early months, and the reviews show a lot of variation” is accurate.
5. Refer when exhaustion or distress is high. Persistent low mood, panic, thoughts of harming oneself or the baby, or inability to sleep even when the baby sleeps need a clinician. Call emergency services for immediate danger.

Limits and uncertainty

Most evidence on night waking is parent-reported and observational, defined differently across studies, and draws on older infants as often as newborns. The Galbally cohort is large and nationally representative but reports an association with maternal-reported waking at 6 months. The Brown and Harries survey is a self-selected sample. The AAP sleep-stage page dates from 2013, and the reviews pool studies from many countries. No source in this review explains why newborn wakefulness peaks at particular times of night or tests interventions to lengthen newborn sleep, so none are offered. This article draws on the abstracts of the research articles and the full AAP pages. Premature babies, babies with medical conditions and babies with feeding difficulties may wake for different reasons.

The bottom line

Frequent night waking in the first months is typical and reflects sleep structure, feeding needs and an immature sleep-wake system, and it consolidates gradually, mostly in the first four months. Research is inconsistent about whether feeding method changes waking and there is no tested way to speed the process in newborns. A doula can normalize, protect safe sleep and parental rest, watch for signs of illness and avoid promising a timeline.

Birth & Baby University’s For Doulas page outlines its postpartum doula training, recertification and mentorship for doulas who support families through the newborn weeks and nights. Confirm that any program meets your certifier’s, employer’s or state’s requirements before you enroll.

This article is for professional education. It is not medical, legal or tax advice. Check the standards of your certifying organization and the rules where you work. For concerns about a baby’s health, contact a pediatric provider or emergency services.

Sources and further reading

• American Academy of Pediatrics. Stages of Newborn Sleep (HealthyChildren.org, last updated September 2013). Read the source
• Galland BC, et al. Normal sleep patterns in infants and children: a systematic review of observational studies. Sleep Medicine Reviews (2012). Read the source
• Henderson JMT, France KG, Blampied NM. The consolidation of infants’ nocturnal sleep across the first year of life. Sleep Medicine Reviews (2011). Read the source
• American Academy of Pediatrics. How Often and How Much Should Your Baby Eat? (HealthyChildren.org, last updated April 2024). Read the source
• Kent JC, et al. Volume and frequency of breastfeedings and fat content of breast milk throughout the day. Pediatrics (2006). Read the source
• Galbally M, et al. Breastfeeding and infant sleep patterns: an Australian population study. Journal of Paediatrics and Child Health (2013). Read the source
• Brown A, Harries V. Infant sleep and night feeding patterns during later infancy: association with breastfeeding frequency, daytime complementary food intake, and infant weight. Breastfeeding Medicine (2015). Read the source

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