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The sleep of a 3-month-old baby

Three months is often a clearing. Evening crying calms down, naps start to look like something, and some babies already string together six hours at night.

Enjoy it, without settling into it. Your baby’s sleep is changing its nature behind the scenes: the adult stages are falling into place, and it will show in the coming weeks.

This month is also the right moment to put a bedtime routine in place. Short, always the same, always in the same order. Not because they will "understand", but because repetition eventually triggers drowsiness on its own.

Sleep per 24 h

13 – 16 h

Of which at night

9 – 11 h

Naps

3 – 4

Awake window

1 h 30 – 2 h

One cycle lasts

~ 55 min

Before putting down

~ 20 min

The key point at this age

What you do now, they will ask for again at 2 a.m.

This is the most useful principle in the whole subject, and nobody had explained it to me. Whatever your baby has at the precise moment they tip into sleep, they will look for at the first micro-waking of the night. Fall asleep at the breast, and they will ask for the breast. Fall asleep in their cot, and they will settle back there. At three months you do not have to decide — but it helps to know the question is coming.

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They fall asleep

Their night at 3 months, minute by minute

    The whole night, at a glance

    To send to your partner, the nanny or the grandparents.

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    The timer: when can I put them down?

    Start it the second they fall asleep in your arms.

    --:--before putting them down

    While you wait, keep them against you and try not to move. The countdown will tell you when their sleep is deep enough for the transfer.

    Keep this tab open. The timer stays accurate even if the screen turns off.

    Sleep becomes adult: the four-month shift

    This is the month that changes everything. The adult stages — light, deep, REM — appear, and your baby stops falling asleep straight into active sleep. The famous "four-month regression" is not a regression: it is a permanent maturation.

    • They now fall asleep through light sleep, no longer through active sleep. The labels on the chart change from here.
    • Between two cycles they wake more fully than before — and notice if the surroundings have changed since they fell asleep.
    • This is the age where "falling asleep alone" becomes a real subject: whatever they have as they fall asleep, they will ask for again at 2 a.m.
    • Naps start to organise themselves into three or four a day.

    The classic trap

    If you take one thing from this month: it does not pass. Your baby’s sleep has changed for good, and that is good news.

    Falling asleep alone at this age

    ✓ Possible

    The pivotal age. Whatever your baby has as they fall asleep, they will look for at the first micro-waking of the night. Fall asleep at the breast, and they will ask for the breast at 1 a.m.; fall asleep in their cot, and they will settle back there.

    Put down awake, a child of this age usually takes 10 to 20 minutes to fall asleep. That squirming is normal.

    How much sleep they need, age by age

    The shaded band is the normal range over 24 hours. Hover to read an age range.

    0h4h8h12h16hbirth6 mo1 year18 mo2 years30 mo3 years
    Total sleep over 24 hOf which at night

    Hover over the curve to read an age range.

    The questions of this age

    Is my three-month-old sleeping enough?

    The normal range is 13 to 16 hours out of 24, naps included. But a baby who sleeps an hour less than average and is alert, smiling and gaining weight is doing fine. You look at daytime behaviour before you look at a total.

    Should I start putting my baby down awake?

    You can try, without expecting a result. At three months the ability to self-settle is only just beginning. Treat it as occasional practice rather than a goal: a few attempts a week, and you stop without guilt on the days it does not take.

    How many naps at 3 months?

    Three to four, with very variable lengths. The late-afternoon nap is often the shortest, and it is the first one that will disappear, around six to eight months.

    One idea a month, no more

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