Should You Let Your Baby Cry It Out to Sleep? What the Studies Say

Past midnight. Your baby has been crying in their cot for ten minutes, and you are standing behind the door, heart tight. An aunt told you that you have to let your baby cry it out so they learn to sleep. Your mother thinks the opposite. And you no longer know whom to believe.

The question divides parents, and professionals too. Recent studies, however, give more nuanced answers than the slogans. Here is what they show, what they do not say, and how to choose what suits your family.

Why you never leave a baby under 6 months to cry

A very young baby cries to express a need. Naître et grandir sums it up this way: they are not crying to manipulate you. Hunger, discomfort, need for contact, tiredness: at this age, they have no other way to call you.

Naître et grandir firmly advises against the 5-10-15 method before 6 months: a baby nobody answers may stop signalling hunger at night, with a risk of dehydration. Santé.fr agrees: before 3 to 4 months, you impose nothing. A newborn often wakes every 2 to 3 hours, and that is normal. If the evening crying wears you out, our article on infant crying helps you decode it.

5-10-15, Ferber, the chair: what are we talking about?

All these methods aim at self-soothing to sleep: your baby falls asleep alone in their cot and settles alone between sleep cycles. They differ mainly in how much crying they leave room for.

The 5-10-15 method dates from the 1950s, Naître et grandir points out. It is also called the Ferber method, or graduated extinction.

What the studies show

Two Australian trials are often cited, and their results are rather reassuring for graduated methods.

The trial by Price and colleagues (Pediatrics, 2012) followed 326 children with sleep problems. Some of the parents learned controlled comforting or the chair method at around 8-10 months, with a nurse. At 6 years, there was no difference between the groups: the child’s mental health and behaviour, stress regulation, the parent-child relationship, mothers’ mental health.

The trial by Gradisar and colleagues (Pediatrics, 2016) compared graduated extinction, bedtime fading and simple advice in 43 babies aged 6 to 16 months. Both methods reduced the time to fall asleep; graduated extinction also reduced night wakings. Salivary cortisol, a stress hormone, did not rise. At 12 months, there was no difference in attachment or behaviour.

What these studies do not say

• They are small or incomplete. The 2016 trial counted only 43 babies. The 2012 one excluded children with developmental disorders, and some population groups were poorly represented in it.
• They do not measure stress in the moment. The cortisol samples did not capture stress during the crying itself. A 2012 American study, cited by CBC, had on the contrary found raised stress hormones in babies subjected to this technique.
• They do not validate the “hard” method. None of these trials evaluated shutting the door and never coming back.
• They do not prove a benefit for development. Naître et grandir stresses that no positive effect on a child’s development has been shown.

In short: these graduated methods, after 6 months, do not seem to cause harm. But they are not compulsory for a child to end up sleeping.

Why recommendations differ

The French-language sources do not say quite the same thing. Santé.fr advises that after 6 months you do not run at the first noise: many babies settle back alone within a few minutes, and stepping in too fast stops them. The same site nevertheless reminds us that “letting a baby scream is terribly distressing for them”.

Naître et grandir puts more emphasis on a quick, calm response, which helps your baby fall back asleep faster. It also reminds us that learning to fall asleep alone is not a condition for sleeping through the night. Both approaches agree on the essentials: not before 6 months, no prolonged crying, and a calm parent. They differ mainly on how long to wait.

Gentle methods, step by step

If you want to help your baby of at least 6 months fall asleep alone, start with the most progressive approach. The Flinders University team that ran the 2016 trial in fact advises trying bedtime fading first.

1. A short, identical ritual every evening: bath, pyjamas, feed or meal, story, cuddle. Santé.fr advises keeping it to around fifteen minutes. Our article on the bedtime ritual gives examples.
2. Put your baby down when they are really sleepy, at the first signs: rubbing their eyes, yawning, staring into space.
3. Lay them down drowsy but still awake, with a little phrase that is always the same.
4. Stay close, with a hand on them if needed, then move a little further away each evening.
5. Go back if they cry hard, reassure them in a low voice, in the half-light, without turning on the light or systematically lifting them out of the cot.

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What you never do

• Leave a newborn to cry, or any baby under 6 months.
• Leave a sick baby to cry, one with a fever, in pain or vomiting: they need you.
• Shut the door and never come back, for hours.
• Shake your baby. The NHS reminds us: however exasperated you are, you never shake a baby, because it can cause serious brain damage.
• Put a pillow, blanket or soft toys in the cot to comfort them: before age 1, the American Academy of Pediatrics recommends a cot free of soft objects, with your baby on their back. Our article on safe sleeping details these rules. The doudou joins the ritual, then goes into the cot after age 1.

Choosing according to your family

There is no single right answer. Some parents sleep with their baby in the bedroom, reassure them at every waking and do well. Others, exhausted, need nights to change. In Moroccan families, the decision is rarely made alone: grandma, mother-in-law, a shared flat or thin walls all count too.

The right criterion is what you can sustain: whether current nights are bearable or not, the energy to follow a method several evenings in a row, and an approach that fits your convictions. If you first want to understand why your baby wakes, our article on when baby doesn't sleep through the night is a good starting point. And if your child is older, see the child who refuses to go to bed.