Sleep training methods: Ferber, cry it out, the chair and what studies show

“He only falls asleep at the breast.” “She wakes up five times a night and only settles in my arms.” You've read about the Ferber method, the chair method and “cry it out.” You've read that this is how you damage their attachment. And you've probably also read the opposite: that it's scientifically proven, that it works in three nights, and that babies who fall asleep on their own sleep through the night.

The short answer: sleep training, the methods for getting a baby to fall asleep on their own, mostly changes what you go through. In a review of 52 studies, 49 found fewer bedtime problems and fewer night wakings reported by parents. But in the two randomized controlled trials in which the babies also wore a motion sensor, the sensor didn't show a difference: they were probably waking just as often, they just stopped calling for you. Other sensor studies did find fewer wakings, too. In several studies, parents in the method group also had fewer symptoms of depression. In the control groups, many problems went away within a few months, and at 6 years the children from families who had been offered a method looked the same as the others, neither worse nor better. No harm was found in what was measured, in healthy babies 6 months and older, but the studies on stress and attachment are few and small. And none of the guidelines we read proposes controlled crying or extinction as a sleep-training method before 6 months. The closest is the American symptom guide for crying under 3 months: if you've fed your baby and nothing calms them, it suggests, as a last resort, letting them fuss in the crib until they fall asleep.

What “self-soothing” means

Almost all babies wake at night. When researchers filmed babies aged 3–12 months overnight, most of them woke at every age, and at 12 months half of them still needed a parent to get back to sleep.

So “self-soothing” doesn't mean “not waking up anymore.” It means being able to slip back into sleep without calling you. In an older study, also based on overnight filming, babies put in the crib awake at 3 months more often fell back asleep on their own after night wakings, while those laid down already asleep were more often taken out of the crib. That's an association, not proof that one causes the other: it could just as well be that the babies who fall asleep easily are the ones their parents manage to put in the crib awake.

Does it work? Fewer calls, not always fewer wakings

In Canada, 235 families with babies aged 6–8 months were split at random into two groups. One learned a version of the timed-checks method: parents went in at intervals that grew from 2 to 10 minutes, with support by phone. The other received only information on child safety. After six weeks:

In the parents' diaries, wakings dropped clearly in the method group, but the sensor recorded almost the same number of wakings in both groups. Something similar showed up in a study from Adelaide, Australia, of 43 babies aged 6–16 months: the diary showed fewer wakings with the checks, while the sensor showed no difference either in time spent awake at night or in total sleep. The authors suppose the babies kept waking but no longer asked for help. The study was small, though: it had fewer babies per group than the authors had calculated they needed. Sensors can also count movements that aren't wakings, so their absolute figure matters less than the comparison between the groups.

Not all studies show the same thing. A 2024 review of 11 studies that used sensors, most of them about informing parents, found fairly consistent effects on the number of wakings and the time to fall asleep, although only two of them had a low risk of bias. But in the two randomized controlled trials above, in babies 6 months and older with sleep problems, the diary and the sensor didn't tell the same story.

That doesn't make the methods useless: a parent who's no longer called five times a night sleeps differently.

With a method and without: what happens over time

The longest study began in Melbourne with 328 mothers who said their 7-month-old had a sleep problem. At half of the child health centers, families were offered, between 8 and 10 months, one to three consultations with a nurse and a method of their choice: the checks, or sitting by the crib and gradually withdrawing. The children were followed until age 6. The share who, according to their mother, still had a sleep problem:

In the families with usual care, too, the problems dropped a lot. The difference at 10 and 12 months had narrowed by 2 years, and at 6 years the researchers no longer found any difference between the groups in anything they measured: sleep, emotions, behavior, closeness to parents, stress, the mother's health. The table has one important limitation: only 100 of the 174 families offered the method came to a consultation, and the comparison is between all the families, not just those who used it.

A smaller study, also from Melbourne, of 156 babies aged 6–12 months with serious sleep problems, showed the same pattern faster: after 2 months, the problem had gone away in 70% of those with the method and in 47% of those whose parents had received only written information about normal sleep. After 4 months, the difference was no longer significant.

A method speeds up something that, in many children, would have happened anyway, more slowly. For an exhausted parent, a few months is no small thing.

What you gain

The most consistent gain in the studies is the parent's. In the Melbourne cohort, mothers' depression scores were slightly lower at 10 and 12 months, and at 2 years depression symptoms showed up in 15% of the mothers in the method group and in 26% in the other. In the Canadian study, after six weeks, parents in the method group had lower depression scores and less fatigue. In the smaller Melbourne study, the effect showed up mainly in mothers who had started out with high depression scores. In the Melbourne cohort, at 6 years, this difference was gone too.

If you're at the end of your rope, that's a legitimate reason to try a method, but a method doesn't replace help for you. If nothing brings you joy anymore, or you feel hopeless or that you can't cope, talk to your doctor, even if you have only a few of these signs; postpartum depression can show up anytime in the first year, and in fathers too. And if you're thinking about harming yourself or your baby, ask for help right away.

Sleep training methods, as they were tested

In 2006, the American Academy of Sleep Medicine (AASM) gathered 52 studies on sleep problems in children under 5, with more than 2,500 children, and rated each method by how solid the evidence was:

The number of children is the total in those studies, not necessarily the number who received the method. The review is old, but its basic conclusion hasn't been contradicted by the studies since: no method has been shown to be better than another in the long run.

Extinction, or cry it out

You put them down awake, leave, and don't respond to crying until morning, but you keep an eye on them and go in if they seem sick, have hurt themselves or are in danger. It's the method with the most studies and one of the highest rated. It's also the one parents rated least acceptable, in the survey described below.

Graduated extinction: timed checks (the Ferber method)

You put them down awake, leave, and go back in at intervals, stay a few seconds or a minute, and soothe them with your voice or your hand, without picking them up. The studies used very different intervals: a fixed 5 minutes, from 2 to 10 minutes, 3 more minutes each time, or from a few minutes on the first night to more than 25 on the seventh. We didn't find any study comparing them with each other, so the interval charts you find online are conventions from books, not tested programs.

The parent in the room and the chair method

Under the same name, “camping out,” the studies tested two different things. In some, the parent sleeps next to the crib for a week, on a mattress, and steps in only very briefly. In a study from Israel that compared this version with the checks, both worked, the effect held at the 6-month follow-up, and babies with a lot of separation anxiety responded better with the parent in the room. In others, the parent stays by the crib until the child falls asleep and gradually moves toward the door, over one to three weeks. That's the chair method, and in the Melbourne studies it was an option few parents chose.

Bedtime fading

You start from the time they actually fall asleep, not the time you'd like them to, then move bedtime earlier by a quarter of an hour at a time. In the Adelaide study, this approach shortened the time to fall asleep about as much as the checks did, by roughly 10 minutes. For night wakings, in the parents' diaries, the clear effect came from the checks; for bedtime fading, the study's text and its graphs don't say the same thing. It's the handiest option if your problem is falling asleep, not the wakings. If you don't know what time to aim for, the wake windows by age in our table give you a reference point.

The bedtime routine

A bath, a massage, something quiet, lights out no more than half an hour after the bath, every evening. In a randomized trial in children from 7 months to 3 years, the routine alone, with no change in how the child fell asleep, shortened the time to fall asleep and reduced wakings within two weeks. Most of the change showed up in the first three evenings. It's the strongest evidence for a no-cry option, with three caveats: the study was funded by a baby products company, it relied only on what mothers reported, and it excluded children who woke more than three times a night or stayed awake for more than an hour. The concrete steps are in the guide to the bedtime routine.

Popular methods we found no studies for

Pick up–put down, the No-Cry method, the “Sleep Lady Shuffle”: we didn't find any study on them in PubMed, the database of the medical literature. That doesn't mean they don't work; it means we don't know.

Ferber, Estivill, controlled crying: the same method under other names

The most searched-for methods are the same method with a different author on the cover. Richard Ferber popularized timed checks in the US in his 1985 book, “Solve Your Child's Sleep Problems.” In Spain, the same idea is the “Estivill method,” after the 1996 book by Eduard Estivill and Sylvia de Béjar, “Duérmete, niño,” translated into Italian as “Fate la nanna” (in English, “5 Days to a Perfect Night's Sleep for Your Child”). In Germany and Poland, the method is known from Annette Kast-Zahn and Hartmut Morgenroth's 1995 book “Jedes Kind kann schlafen lernen,” which German pages describe the same way, with the parent going in at longer and longer intervals. In Australia it's called “controlled crying,” and online you'll also find it by its intervals: “5-10-15” or “3-5-7.”

None of the books has been tested as such. They borrow the evidence for graduated extinction. Nor do the figures that circulate about them hold up at the source: “The Estivill method works for 95–98% of children” appears on many websites, but not in the review published by Estivill himself, which reports only that the method had been used with more than 300,000 children.

How long it takes

We didn't find any controlled study that counted how many nights each method needs. The “3–7 nights” or “two weeks” you see online are the length of the programs in studies, or rules from guidelines. What does exist:

• in a randomized trial of an online advice program, the improvements mothers reported showed up after one week and grew in the second;
• in a survey of parents who had used a method, the typical time to finish was 7 days, and 79% had finished within two weeks;
• in a small study, only a third to a half of families saw an improvement after three weeks, but almost all did after four months;
• Australian guides for parents say “from 3 days to 3 weeks,” and for gradual withdrawal, “one to three weeks.”

“Night 3 is the hardest” has no source. In the same parent survey, the most common answer was the first night: 45% of parents said so, with an average of 43 minutes of crying. After a week, crying had dropped to under 9 minutes on average. The term “extinction burst,” the flare-up after extinction, also has another meaning in the medical literature: in the AASM review and in the Australian family doctors' guideline, it's the problem coming back after a while, when it seemed solved. We didn't find any study that measured how often this happens or how long the return lasts.

The Australian family doctors' handout for parents tells you that you can stop at any time: you can pick them up, or even let them fall asleep in your arms, and try again another night. And if you see no improvement after 5–7 nights, ask your doctor for advice.

Is sleep training harmful? What studies say about crying, stress and attachment

This is where the internet is most sure of itself, in both directions, and where the studies are fewest.

Cortisol. In the Adelaide study, cortisol was measured in saliva, in the morning and in the afternoon, not during crying. In the morning, the groups didn't differ. In the afternoon, levels fell more in the method groups than in the control group. Overall, the study's abstract talks about decreases, not increases. The claims about “cortisol that stays high” come from a single study of 25 babies aged 4–10 months admitted for five days to a sleep center, with no comparison group: on the third day the babies no longer cried at bedtime, and the authors described their cortisol as elevated, without the abstract saying compared with what. A later pilot study, with cortisol analyzed in 17 babies, found no differences between the groups.

Attachment. In the Adelaide study, attachment was assessed with the standard lab test 12 months after the method: no difference. In the Melbourne cohort, at 6 years: no difference in closeness between child and parent. A UK study of 178 children, which only asked mothers whether they had ever left their baby to cry, found no link with attachment at 18 months. But it wasn't a study of a sleep method, and 41% of the children had been born very early.

What hasn't been shown, in either direction. We didn't find any study of sleep methods that measured babies' brains: “it damages their brain” is an extrapolation from studies on neglect and chronic stress. But “it strengthens attachment,” as the website of a major American hospital says, hasn't been shown either: the study it links to found no difference. The AASM review says babies became “more secure,” but based on old, non-randomized studies, with security rated by parents.

No harm was found in what was measured, a year after the method and at 6 years. But “no evidence of harm” isn't “evidence of no harm.” In the Adelaide study, the groups had 14–15 babies each, and after 3 months 23 of the 43 were left. Cortisol wasn't measured during crying. At 6 years, 69% of the families were still in the study.

That's also why organizations disagree with each other, sometimes even within the same country. The AASM considers the methods effective, and the Australian family doctors' guideline includes controlled crying and staying by the crib for babies aged 6–12 months with serious sleep problems. The Australian parenting services Tresillian and Karitane, however, don't recommend controlled crying, and Raising Children Network, the parenting website funded by the Australian government, took down its page on it by March 2022 at the latest and now recommends responsive settling and bedtime fading. The Australian association for infant mental health says extinction methods aren't appropriate before a baby understands what the parent's words mean.

When to start sleep training

We didn't find any study that compared starting ages, and the organizations, mostly on pages for parents, give different ages:

• the American Academy of Pediatrics' page for parents tells you to put your baby in the crib drowsy, not asleep, from 4 months;
• the Canadian Paediatric Society and Raising Children Network talk about settling them in the crib without taking them out, or about staying next to them, from around 6 months;
• Australia's family doctors don't recommend controlled crying under 6 months, and between 3 and 6 months they say you can encourage your baby to fall asleep on their own without letting them cry for more than a minute or two;
• the official German child health portal says sleep-learning programs are, as a rule, recommended only from one year, and under no circumstances earlier.

The large randomized trials of the methods included babies 6 months and older. “The 4–8 month window, the easiest one” doesn't come from any study. And under 6 months, night feeds are a real need: even at 6–12 months, in a UK survey, 79% of babies woke at least once a night and 61% were still feeding at night, at the breast or from a bottle.

For the first months, something else was tested: explaining to parents how to make day and night different, to sometimes put the baby in the crib awake, and to wait a minute or two before going in. Four large studies, from Canada, Australia, New Zealand and Brazil, found no difference that mattered in the babies' sleep. In the one from Brazil, in Pelotas, only 13% of the mothers who had been shown how to put their baby down awake actually did it, compared with 11% in the control group. Evening crying in the first months has other causes, which you'll find in the guide to colic, and for the change at 4 months, in the one on the sleep regression.

The studies included healthy babies who were gaining weight normally. If your baby was born prematurely, is growing slowly, or has a health problem their doctor is keeping an eye on, talk to your pediatrician first. The same Australian handout says to start only when your baby is well and you have a few free nights, so not when they're sick or right after a move or a trip; and if they get sick partway through, you stop. Crying that's different from usual, or that you can't soothe at all, can be a sign of illness, says the NHS, Britain's public health service, so that's when you go in. If they have a fever or won't feed, call your pediatrician; if they're floppy, hard to wake, struggling to breathe or projectile vomiting, call 911 or go to the ER.

If you don't want to let them cry

You have three options, all of them legitimate.

• Do nothing special. In many children, the problem passes without a method too, just more slowly. If the way things are now works for your family, you have nothing to fix.
• Change what surrounds falling asleep. An identical routine evening after evening and a bedtime matched to how tired they really are, not to the clock. Both have been tested in randomized trials.
• Stay with them. In the Israel study, the version where the parent sleeps in the room and steps in only briefly worked too, and gradual withdrawal toward the door is what the Australian centers use.

The honest promise is “less crying, with you beside them,” not “no crying”: almost any change in how they fall asleep brings protests at first. Gentle doesn't automatically mean easy to stick with. In a 2026 survey of parents in five countries, the chair method was the one most often abandoned: 56% of those who had started it gave up before the end, compared with about 48% for the checks, 41% for extinction and 37% for the approach where you respond to crying and gradually withdraw your help (we calculated those three ourselves from the study's table). The parents who got their baby to sleep in their arms gave up least often, 28%. No method was acceptable to more than 44% of parents, and extinction to only one in ten.

How to choose and how to start

• Choose what you can stick with. In the Israel study, parents who tolerated crying better got better results, and the AASM review names parents' lack of consistency as the biggest obstacle to extinction. The right method is the one you can repeat on the fifth evening, not the fastest one on paper.
• Decide together, ahead of time. Which method, what you do when they wake, what you do about night feeds (which you discuss with your pediatrician), and after how many evenings you stop.
• The safe sleep rules stay the same. On their back, on a firm, flat mattress, in their own crib, with no pillows, loose blankets, bumpers or toys, in your room for at least the first 6 months; if you sleep next to them on a mattress, they stay in the crib. If you soothe them in your arms at night, put them in the crib before you fall asleep: falling asleep together on a couch or in an armchair raises the risk of sudden infant death.
• If you feel you can't take any more, leave the room. Put them safely in the crib, close the door and take ten minutes or so, as the NHS recommends, then go back. However hard it gets, never shake your baby.
• Not every waking calls for a method. A child who wakes up screaming from a night terror doesn't have a problem falling asleep.
• Watch the trend, not the hard night. The bad night sticks in your memory; slow progress doesn't.
• If nothing changes, stop. Sometimes the problem is something else: reflux, breathing during sleep, a bedtime that doesn't fit. You can go through them, in order, in the guide why your baby won't sleep.

How Lulla helps

When you stop the timer after a sleep, Lulla opens a sheet. Under “How they fell asleep” you pick a single option, for example “On their own,” “Breastfed” or “In our arms,” and under “Awakenings during sleep” the counter starts from the number of pauses you made, and you correct it with + and −. In History you'll find them when you tap a sleep, under “Details” and “Awakenings,” so after a few evenings you can compare whether “On their own” comes up more and more often and whether the wakings are going down. Lulla doesn't measure separately how long it takes to fall asleep: the timer keeps a single interval, so start it when they fall asleep, not when you put them in the crib, and write the minutes it took to fall asleep under “Notes.”

Keep in mind what the sensors showed, too: what you log are the wakings when they call for you, not all wakings. For a sleep method, that's exactly the figure you care about. If you're both using the same method, “Share with family” lets you see the same history. The invite code is generated by a parent with Premium, and the other parent enters it for free when first setting up the app, at the “How many little ones are we tracking?” step. The steps are in the sharing guide.

Falling asleep on their own is a useful skill, not an obligation and not a test of being a good parent. If you've already used controlled crying, even Tresillian, which doesn't recommend it, says that doesn't define your child's attachment or development. This article is for information, not medical advice: for any concern about your child's sleep, growth or condition, or about how you're doing, talk to your doctor first.

The sleep schedule by age, with the bedtime and wake windows to start from:

Newborn · 1 month · 2 months · 3 months · 4 months · 5 months · 6 months · 7 months · 8 months · 9 months · 10 months · 11 months · 12 months · 13 months · 14 months · 15 months · 16 months · 17 months · 18 months · 19 months · 20 months · 21 months · 22 months · 23 months · 24 months