Newborn sleep: what to expect (0–3 months)

Newborns spend roughly half their sleep in active REM (vs about 25% in adults)^[2], which is why they twitch, vocalise, and look like they're about to wake at the smallest sound. They're often deeply asleep through what looks like restless behaviour — the rule of thumb is: don't intervene unless they fully wake.

Wake windows at this age are short — 45 to 90 minutes between sleeps. Stretching beyond that produces an overtired baby who paradoxically fights sleep harder, not falls asleep faster. Watch for the early cues: glassy stare, ear-pulling, looking away. By the time crying starts, you've usually missed the easiest window.

Sleep cycles are also shorter than they will become — about 50 minutes vs 90 minutes for adults^[2]. This is why newborns often wake every 45 minutes and need help re-settling. The full 90-minute adult cycle structure consolidates between 4 and 6 months — what gets called "the 4-month regression" is actually this maturation event.

For roughly the first six weeks, your baby has no internal day/night clock. The system that produces melatonin in response to darkness develops between weeks 6 and 12, gradually^[3]. Until then, baby may sleep 4-hour stretches at noon and 90-minute stretches at midnight — and that is biologically correct.

You can help the day/night sort itself by being boring at night and engaging during the day. Bright daylight + talking + activity in the day; dim lights, hushed voices, minimal stimulation at night. The rule: night feeds happen but stay quiet, dim, and businesslike. By 8-10 weeks, most babies have started to consolidate the longest sleep stretch into the night^[3].

Newborns wake to feed every 2-3 hours during the day and every 3-4 at night for the first several weeks. Breastfed babies tend to wake more often than formula-fed because breast milk digests faster, and that is normal — it does not mean breast milk is "not enough."

Don't try to push longer stretches before about 6 weeks unless your pediatrician has cleared it on weight gain. Premature attempts to extend night sleep can suppress milk supply (for breastfeeding parents) or compromise weight gain. The longest sleep stretches lengthen on their own as the baby's stomach grows.

If your baby is sleeping through feeds in the early weeks, especially during the day, gently wake them. Newborns are sleepy and can under-feed without crying for it, which can cascade into weight issues. Past 6 weeks and growing well, you can stop waking for daytime feeds.

At this age, safe sleep practices outrank schedule consistency. The American Academy of Pediatrics 2022 guidelines^[1]: baby on their back, on a firm flat surface (crib or bassinet), no loose blankets or pillows or stuffed animals, no incline sleepers, and ideally in the parents' room (not bed) for the first 6 months.

White noise at the crib at safe levels (≤ 50 dB at 1 meter^[4]) can help with the startle reflex that wakes many newborns. Swaddling helps for the first 8 weeks or until rolling starts. After rolling begins, swaddling becomes a safety risk and must stop^[1].

What's not on the safe sleep list: anything that promises to keep baby asleep longer through positioning, propping, or restraining. Inclined sleepers were recalled in 2019 for this reason. Stick with a flat firm surface and the basics.

Normal: 8-12 wakings per 24 hours, two-to-four-hour sleep stretches, day/night confusion, lots of REM twitching, occasional loud breathing during active sleep, "witching hour" fussiness in the evening that does not respond to anything you try.

Worth noticing but probably normal: a sudden return to more frequent waking around 6-8 weeks (often the result of a developmental leap, not regression). A growth spurt around weeks 3, 6, and 12 (extra waking + extra hunger for 2-3 days)^[5].

Flag for your pediatrician: any extended period of "very easy" sleep where baby sleeps through feeds and is not gaining weight; lethargy that is hard to rouse from; persistent strong arching during sleep (can indicate reflux); breathing pauses longer than 20 seconds (most pauses under 20s are normal periodic breathing^[5]).