Wake Windows for a 4 Month Old

A four-month-old usually manages an hour and a half to a bit over two hours awake between sleeps — 1 hr 30 to 2 hr 15 — across three or four naps, inside a total of 12 to 16 hours of sleep per 24 hours. Four months is also the first month that total exists at all, because the consensus statement every band on this site is built from starts at four months and deliberately publishes nothing below it. So the arithmetic gets firmer this month at exactly the moment the baby gets harder. Both things are the same event, and this page is about that event.

If you have arrived here because a baby who slept fine in February is now up every hour, you are in the right month and nothing has gone wrong.

The band at four months

An hour and a half at the short end, two and a quarter at the long end, three or four naps in the day. The wake windows by age table shows how that sits either side of it — a quarter of an hour longer than three months, and unchanged at five, which is a fact worth holding on to.

What is new is the bottom of the sum. The American Academy of Sleep Medicine's consensus gives 12 to 16 hours per 24 hours including naps for infants from four to twelve months, and declines to give any figure under four months because the normal variation is too wide to be useful. Everything written about a two-month-old's day, here and everywhere else, is compiled out of thin air by comparison. From this month there is a published total to subtract a night from, which is why the bands stop being guesswork and start being arithmetic. The overview does that subtraction in full, and the wake window calculator will add the band to the clock for you.

One pattern inside the band, and it is a rule of thumb rather than a finding: the first stretch of the morning usually sits near the short end and the last before bed near the long end. A baby who is fine on 95 minutes at seven in the morning may want two and a quarter hours at five in the afternoon.

What actually changed: her sleep grew a shape

The American Academy of Pediatrics puts it in one line: babies do not have regular sleep cycles until about four months of age. Before this month, sleep was mostly one long soft thing that ended when it ended. Around now it organises into cycles, and cycles have ends. She comes up close to the surface between them, notices where she is, and either goes back down or does not.

That is the whole mechanism, and almost everything parents report this month falls out of it. If she went to sleep on you, or on the breast, or being walked round the kitchen, then the conditions she surfaces into at half past one are not the conditions she went down in, and she says so. It is not a habit she has picked up and it is not something you taught her. It is a nervous system that has started keeping time.

The same guidance is where the drowsy-not-asleep suggestion comes from: from four months the AAP suggests putting a baby to bed drowsy rather than fully asleep, so that falling asleep and the cot are one event. Plenty of babies decline. Try it at the first nap, which is usually the easiest, and do not fight over it at eleven at night.

The thirty-minute nap

This is the problem four months hands most families. A nap starts, one cycle runs out, and she is awake and cross with a third of a nap in her. It is not a fault in her or in the room.

What tends to help, in the order worth trying it: leave her five or ten minutes before you go in, because a fair number of babies join the next cycle on their own if nobody opens the door; make the room genuinely dark, since the second cycle is the light one; and if the first nap of the day is the one that keeps breaking, take ten or fifteen minutes off the window before it rather than adding them. Then let a short nap move the whole day forward instead of holding her to the clock. Four short naps is an ordinary four-month day.

The evening version of the same thing is the false start: down at seven, up at ten to eight, furious. Same mechanism, first cycle of the night, and it usually answers to the same two things — a slightly shorter last window and a settle she can repeat without you.

Rolling is coming, so the swaddle comes off now

Rocking on the stomach, kicking and swimming with the arms usually appear at about five months, and the AAP names those as the skills that lead to rolling over and crawling; by the end of that period most babies roll in both directions, though the timing varies a lot between babies. Which makes four months the month to deal with the swaddle, while it is still a choice rather than an emergency.

The reason is simple and it is a safety one: a swaddled baby who rolls onto her front cannot push herself back up or free her arms. So arms out at the first sign of rolling, and preferably a week or two before. No source listed below names a month for it — that is the cautious reading of the safe-sleep guidance rather than a published instruction, and it is the one this site takes.

The rest of the safe-sleep guidance does not move: on their back for every sleep, day and night, on a firm flat surface, in a cot clear of blankets, pillows, bumpers and soft toys, in your room for at least the first six months. Nothing weighted goes on or over a sleeping baby, whatever it is sold as. If she rolls onto her front by herself once she can roll both ways, you put her down on her back and you do not need to spend the night turning her over.

Expect a rough few nights when the arms come out. One arm first, then both, over about a week, is easier on everybody than doing it in one go — though some babies prefer both arms free straight away, and that is worth finding out.

The fourth nap starts to wobble

Three or four naps is the band, and the fourth is the one that goes. It is usually a short late-afternoon catnap that has been holding bedtime at a civilised hour, and this is the month it starts refusing to happen: she lies in the dark being cheerful for forty minutes, and then bedtime is a disaster because she has been awake for four hours.

The move from four naps to three happens somewhere around three to five months, and no health body publishes a schedule for it. The honest signal is a pattern rather than one bad afternoon — a fortnight of the last nap failing more often than it works — and the answer is to bring bedtime forward on the days it fails rather than push her through to the usual hour. The 4 to 3 nap transition page has the whole of it.

The four-month regression, said plainly

Everything above is what the internet calls the four-month sleep regression. It is worth knowing two things about that name.

The first is that no publisher this site is allowed to cite uses the word regression, publishes the famous list of ages, or attaches a number of weeks to any of it. What is published is the sentence at the top of this page: sleep cycles arrive at about four months.

The second is the part that matters at 3am, and it is why this month is different from every other name on that list. This is not a phase that passes and hands your February baby back: her sleep has changed shape permanently, in the direction of adult sleep. What passes is the disruption while she learns to get from one cycle to the next, and that is learning rather than waiting. The 4 month sleep regression page covers it properly, and the regression timeline puts it beside the other ages people use the word about.

What to change, and what to leave

Change one thing and give it three days. The first window of the morning is usually the highest-value fifteen minutes on the board, because every other sleep in the day is downstream of it. Write down what happened: four days of your own notes will beat this page, which is the whole argument for keeping them. The sleep schedule generator will stack the bands into a sample day if you want somewhere to start.

And leave the rest. Your baby will have her own pattern of waking and sleeping, and it is unlikely to be the same as other babies you know — the NHS says so first, before any advice at all. If what worries you is not the timing but the baby — feeding, weight gain, a baby who cannot be settled at all, a cry that does not sound like her usual one — that is a conversation with your pediatrician or health visitor. Nothing here is medical advice and no page can see your baby.