AAP Safe Sleep Guidelines (2022)American Academy of Pediatrics — always follow these guidelines
Always
Never
Baby Sleep by Age: What Is Normal
Month-by-month sleep development from newborn to 12 months. Understand how baby sleep architecture evolves, what the 4-month regression actually is, and how to tell what is normal variation from something worth discussing with your paediatrician.
Month-by-Month Sleep Guide
Select your baby’s age to see typical sleep totals, nap patterns, and the key developmental sleep milestone for that stage. These are population averages — individual variation within these ranges is common and normal. If your baby falls significantly outside these ranges and you are concerned, speak with your health visitor or GP.
The 4-Month Sleep Regression: Developmental Progress, Not a Problem
The 4-month sleep regression is the most-searched baby sleep topic and the most misunderstood. It is not a regression – it is a permanent and positive developmental milestone. Understanding what actually changes helps parents respond with appropriate expectations rather than trying to return to something that no longer exists.
Before 3.5 months: 2-stage sleep
Active and quiet sleep only
After 3.5-4 months: 4-stage adult architecture
N1, N2, N3, and REM — just like adults
How to support the transition:
Understand what is happening: this is not a problem to solve but a developmental milestone to support. Lowering expectations for night sleep at 4 months reduces parental stress significantly.
Consistent bedtime routine: a predictable short routine (bath, feed, song, sleep) helps the developing circadian system associate cues with sleep onset. This is appropriate from around 3-4 months.
Drowsy but awake: placing baby in their crib drowsy but awake — when developmentally appropriate, typically 4-6 months — gives them the opportunity to practise falling asleep independently, which transfers to cycle-end self-settling. This approach should always respect baby’s developmental readiness and parental values.
Safe sleep always applies: regardless of sleep training approach, all AAP safe sleep guidelines apply at all times. No sleep training method overrides safe sleep requirements.
How the Circadian Clock Develops: Birth to 6 Months
Babies are not born with a functioning circadian clock. The biological rhythm that governs adult sleep-wake cycles develops gradually over the first 3-4 months of life, driven by environmental cues – particularly light and feeding. Understanding this timeline explains why newborn sleep appears chaotic and why expecting a newborn to “sleep through the night” is a developmentally unrealistic expectation.
Birth – 4 weeks
No circadian rhythm
Sleep is governed entirely by hunger, comfort, and homeostatic sleep pressure. Day and night are indistinguishable to the newborn. Sleep occurs in 2-4 hour windows around feeding cycles, distributed evenly across 24 hours. The absence of a circadian clock is not a failure – the clock simply has not yet been calibrated to the external world.
4-6 weeks
First day/night signals emerging
The first hints of day/night preference begin to appear. Babies start showing slightly longer sleep periods at night and more alertness during the day. Exposing the baby to natural daylight during daytime feeds and keeping night feeds quiet and dim helps reinforce this early circadian signal. The development is fragile and easily disrupted.
6-8 weeks
Social smiling and circadian cortisol
The morning cortisol rise – a key circadian signal – begins to emerge. This is the same physiological process that wakes adults, and its emergence in babies starts anchoring sleep to the dark phase. Social smiling also begins, a sign of broader neurological maturation that parallels circadian development.
2-3 months
Night sleep consolidating
Many babies show a longer consolidated night stretch of 4-6 hours. Melatonin production begins to show a nocturnal rhythm. This consolidation reflects circadian clock maturation, not parenting technique – it happens on a biological schedule. Parents who achieve longer nights at this stage should not assume they have “fixed” anything that will persist through the 4-month architecture shift.
3.5-4 months
Sleep architecture shift (the “regression”)
The two-stage newborn sleep pattern (active/quiet) permanently transitions to the adult four-stage pattern (N1/N2/N3/REM). Night wakings increase as babies now arouse briefly at each cycle end. The circadian rhythm is becoming more robust but the new sleep architecture creates new demands on self-settling ability.
5-6 months
Circadian rhythm well established
By 6 months, most babies have a well-established circadian rhythm with robust melatonin secretion. Sleep becomes more predictable in timing. Nap windows consolidate. Many babies are physiologically capable of longer night stretches (though not all will achieve this without support). Light exposure during the day and darkness at night are now highly effective circadian anchors.
When to Speak to Your GP or Paediatrician
These guidelines are for typically-developing healthy babies. Always contact your GP, health visitor, or paediatrician promptly if your baby shows any of the following:
This page provides general educational information. It does not replace individual medical advice. All decisions about your baby’s health, feeding, and sleep should involve your own healthcare team.
Sleep Cycle Calculator
For Parents: Calculate Your Own Sleep Cycles
Understanding your own sleep architecture helps you optimise the limited sleep you are getting. The sleep cycle calculator finds the wake times that minimise morning grogginess regardless of how little you slept.
Calculate Your Sleep CyclesFrequently Asked Questions
How much should a baby sleep?
Sleep needs change rapidly across the first year. Newborns (0-3 months) typically sleep 14-17 hours across 24 hours with no day/night distinction. By 4-6 months, 12-15 hours is typical, with more sleep consolidated into the night period and 3-4 naps during the day. By 9-12 months, most babies sleep 12-14 hours total, typically 10-12 hours overnight and 2-3 hours across 2 daytime naps. Individual variation within these ranges is very common and does not indicate a problem. Babies who consistently sleep significantly outside these ranges, or who show signs of breathing difficulty, feeding problems, or developmental concerns, should be assessed by a GP or paediatrician.
What is the 4-month sleep regression?
The 4-month sleep regression is not a regression – it is a permanent developmental milestone. At approximately 3.5-4 months, babies permanently transition from a two-stage sleep pattern (active and quiet sleep, the newborn pattern) to the adult four-stage pattern (N1, N2, N3 deep sleep, and REM). With this new architecture, babies now cycle between sleep stages and briefly arouse at each cycle end – exactly as adults do. Adults self-settle through these brief arousals without waking. Babies who have learned to fall asleep only with feeding, rocking, or holding now need that input again at each cycle end. This is why night wakings increase dramatically at 4 months. The pre-4-month sleep pattern does not return – this is the new normal, and the focus shifts to supporting the baby’s developing ability to self-settle at cycle transitions.
Should I wake my baby to feed at night?
This depends on your baby’s age, weight, and specific medical situation – it is not a question this page can answer definitively. For newborns, particularly those who lost more than 10% of birth weight or have feeding concerns, healthcare providers typically recommend waking to feed every 2-3 hours until weight gain is established. For healthy term babies who have regained birth weight and are feeding well, many healthcare providers advise following the baby’s hunger cues. The specific guidance for your baby should come from your GP, health visitor, or paediatrician, who can account for your baby’s individual growth curve, feeding method, and health status. Always follow the individualised advice of your own healthcare team on feeding schedules.
