Cry it out (extinction): how it works, ages and the evidence

Cry it out, known in research as unmodified extinction, means putting your baby to bed at a set bedtime and not going back in until morning, except to check for safety and illness. That's how the American Academy of Sleep Medicine (AASM) defines it. It is the most hands-off of the sleep training methods, and it's different from controlled comforting, where you check on your baby at intervals. Australian and UK sources say methods like this aren't for babies under 6 months, and the evidence is a mix of real benefits for sleep and open questions about stress.

This guide explains the method neutrally so you can decide. It isn't a recommendation to use it, and plenty of families choose gentler options or no sleep training at all.

What is the cry-it-out method?

In the AASM definition, parents put the child to bed at a designated bedtime and then ignore the child until morning, while continuing to monitor for safety and illness. The aim is to reduce crying and calling out by removing parental attention as a reward for it.

The NCT draws the line between two methods that are often confused:

• Cry it out (extinction): you leave your baby to cry and don't respond at all.
• Controlled crying (graduated extinction): you check in on your baby to let them know you're there, but don't soothe them back to sleep. The NCT notes this is sometimes called the Ferber method.

If you're interested in checking at intervals, see check and console, which covers controlled comforting in full. The AASM also lists a variant called "extinction with parental presence", where a parent stays in the room.

Where does cry it out come from?

The name comes from behavioural psychology, where "extinction" describes a behaviour fading once it stops being rewarded. Sleep researchers study it under the name "unmodified extinction", and it was one of the therapies assessed in a 2006 AASM review of 52 treatment studies.

Australia's Tresillian, the Australian parenting service, describes "crying it out" as a newer name for controlled crying, a method used in the 1980s, and says newer infant mental health research has shown gentler ways to support sleep.

What age is cry it out used from?

Sources that give an age put it at 6 months or older:

The NCT explains its reasoning: encouraging babies under 6 months to sleep longer and deeper than is normal for their stage could increase the risk of SIDS, and sleep training often means a separate room, while room-sharing day and night for the first six months helps protect against SIDS. A systematic review by Douglas and Hill found behavioural sleep interventions in the first 6 months hadn't been shown to reduce crying, prevent later sleep problems or protect against postnatal depression.

In the US, HealthyChildren.org's guide to getting your baby to sleep (from the American Academy of Pediatrics) doesn't name a sleep training method or an age for one. It suggests putting babies to bed drowsy rather than asleep and not rushing in to soothe a crying baby, because babies need time to learn to fall back asleep on their own.

If your baby was born premature, ask your GP or health visitor whether to go by their corrected age.

How is cry it out done, step by step?

If you've decided to try it, this is how the method is usually set up. It's worth talking it through with your GP or health visitor first, especially if your baby has any health or feeding concerns.

1. Check the timing. Your baby is over 6 months, well, feeding and growing as expected, and there's no big upheaval such as illness or a move.
2. Get everyone on the same page. The RACGP lists parents disagreeing about how to manage sleep as one reason a sleep plan doesn't work. Agree on the plan, including what you'll do overnight, before night one.
3. Decide about night feeds. The NHS says that from 6 to 12 months night feeds may no longer be needed, but some babies still need them. If your baby is still feeding overnight, talk to your health visitor and see dropping night feeds.
4. Meet their needs first. HealthyChildren.org suggests checking for hunger, tiredness or pain before anything else. A full feed, clean nappy and comfortable clothes come first.
5. Set up the cot safely. On their back, on a firm flat mattress with a fitted sheet only (see the safety section below).
6. Do a calm, predictable bedtime routine at the same time each night. See bedtime routine.
7. Put your baby in the cot awake, say goodnight and leave.
8. Don't go back in until your set morning time, except to check on safety and illness. Listening out, or using a monitor, lets you check without going in.
9. Keep a sleep diary. The RACGP program gives parents a diary to track progress. Note bedtime, how long crying lasted, wakings and the morning wake time, so you can see the trend rather than judge single nights.

What does a typical first week look like?

There's no reliable night-by-night pattern, and babies vary a lot. Many families find the first nights the hardest, and how quickly crying eases differs from one baby to the next, which is why a diary helps. Expect to need your agreed plan for the middle of the night, not just bedtime.

The RACGP program reviews progress after 2 weeks. It also warns about an extinction burst: a return of night waking 2–4 weeks after it stopped, which happens in about 20% of babies, without an obvious cause such as a fever. The advice is to go back to the same technique, and babies typically settle back into their new sleep habits after a few nights.

If nothing has improved after a couple of weeks, the RACGP suggests looking at whether the technique is being used consistently, whether parents disagree about it, and whether a parent may be depressed.

Does cry it out work? What the evidence says

The research supports extinction for sleep, but most studies don't measure everything parents care about, and few test full extinction on its own.

Evidence it improves sleep

• The AASM review of 52 studies found 94% reported behavioural treatments worked, with over 80% of children showing clinically significant improvement that lasted 3 to 6 months. It found strong support for unmodified extinction.
• The AASM's 2006 practice parameters rated unmodified extinction a "standard" (the highest level), but found insufficient evidence to recommend any single method over another.

Evidence about long-term effects

• An Australian randomised trial by Gradisar and colleagues with 43 babies aged 6–16 months tested graduated extinction (with checks, not full extinction) and bedtime fading. Both improved sleep. Cortisol (a stress hormone) showed small-to-moderate declines, and 12 months later there were no differences in attachment, emotions or behaviour.
• A 5-year follow-up of an Australian trial of nurse-delivered behavioural sleep techniques at 8–10 months found no differences at age 6 in emotional or behavioural problems, stress, the child-parent relationship or mothers' mental health. The authors concluded the techniques had no marked long-lasting effects, positive or negative.
• A UK study by Bilgin and Wolke followed 178 babies whose parents reported how often they left them to cry it out. Doing so in the first 6 months wasn't linked to poorer attachment or behaviour at 18 months. This was an observational study, not a trial of a sleep program.

Concerns researchers have raised

• A small study by Middlemiss and colleagues of 25 babies aged 4 to 10 months in a 5-day inpatient extinction program found that by day 3 babies no longer showed distress at sleep time, but their cortisol was still raised, while their mothers' had fallen.
• Douglas and Hill warn that sleep interventions used from the first weeks risk more problem crying, earlier weaning from the breast and more maternal anxiety.
• HealthyChildren.org stresses that teaching a baby to self-soothe is not the same as making them "cry it out" or ignoring their cries.

In short: extinction has good evidence for reducing bedtime problems and night waking in older babies, trials of related methods haven't found long-term harm, and questions about short-term stress remain.

Who does cry it out suit, and who doesn't it suit?

It may suit families where:

• your baby is over 6 months, healthy and growing well
• night waking or long bedtimes are wearing the family down
• both parents agree and feel able to stick with it
• gentler methods haven't worked, or you'd rather a short, consistent approach

It's not a good fit when:

• your baby is under 6 months
• your baby is unwell, in pain, or has feeding, weight or medical concerns (talk to your GP first)
• you're going through a big change such as a move, new childcare or a new sibling
• listening to crying feels unbearable. The RACGP advises considering the impact of each method on parents, and responsive settling or gradual retreat may suit you better
• a parent is struggling with low mood. Get support for that first; see postnatal mood

What safety rules apply, and when should I stop?

The safe sleep basics apply to every sleep, whatever settling method you use. NICHD Safe to Sleep and Australia's Red Nose advise:

• on their back to sleep, with head and face uncovered
• a firm, flat, level mattress with only a fitted sheet, and nothing soft or loose in the cot
• no weighted sleeping bags, swaddles or blankets
• their own safe sleep space in your room for at least the first 6 months
• a smoke-free environment

NICHD advises placing babies on their back for every sleep, including naps, until they are 1 year old. See safe sleep for the full set-up.

Stop and go in if crying sounds different, your baby has vomited, or you think they're sick. Use the NHS urgent help guide:

See a GP today if your baby has a fever and seems unwell, isn't feeding, or you're worried. Put the plan on hold until they're better.

Look after yourself, too. If the crying is too much, it's fine to stop. If you feel at the end of your tether, put your baby safely in their cot and step away for a few minutes, then call your health visitor, or NHS 111. If you have thoughts of harming yourself or your baby, call Samaritans on 116 123 or 999.

How does cry it out compare with other methods?

For a side-by-side look at every option, see the sleep training overview. The AASM found no method clearly better than the others, so the best one is usually the one your family can do consistently and feel comfortable with.