Why is my baby awake all night and asleep all day?

In the womb there was no daylight, no quiet hours, no schedule to learn. So the newborn brain starts from zero on day and night, and the reviewed guidance sets a realistic timeline for when rhythm appears:

Babies usually do not develop regular sleep cycles until about 4 months of age.AAP HealthyChildren · 0-4 months

Reviewed wording: "Babies usually do not develop regular sleep cycles until about 4 months of age."

Applies to: 0-4 months · Source: AAP HealthyChildren, Getting Your Baby to Sleep · Reviewed by the LEELALU team (editorial review) · Reviewed: July 2026 · Status: current · Claim ID: sleep.no_regular_cycles.0_4m.v1

While the clock builds itself, you are the main source of time cues. The one habit the guidance points to is contrast:

Keeping daytime light and lively and nighttime dark and quiet helps a newborn gradually learn the difference between day and night.NHS · 0-3 months

Reviewed wording: "Keeping daytime light and lively and nighttime dark and quiet helps a newborn gradually learn the difference between day and night."

Applies to: 0-3 months · Source: NHS, Helping your baby to sleep · Reviewed by the LEELALU team (editorial review) · Reviewed: July 2026 · Status: current · Claim ID: sleep.day_night_learning.0_3m.v1

Notice the word gradually. The mixed-up phase is not something you caused, and it is not something you can rush out of. Days that feel like daytime and nights that feel like nighttime are the whole strategy; the maturing brain does the rest on its own timeline.

Two minutes, two moves. Tonight, make the night feed as boring as possible: lights low, voice soft, no entertainment. Tomorrow morning, do the opposite: open the curtains at the first feed, let daylight in, chat and hum through the routine. You are not forcing sleep, you are labeling the hours so the lesson sinks in day by day.