Cry It Out (CIO) Parenting

What is cry it out?

“Cry it out,” often shortened to CIO, is a way of sleep training in which caregivers put a baby down to sleep and do not step in right away when the baby cries. The idea is that the baby gradually learns to fall asleep without being rocked, fed or held to sleep every time.

People use the term in different ways, which is part of why the topic gets so heated:

• Full extinction: the caregiver puts the baby down and does not return until a set time or morning, unless there is a safety or health concern.
• Graduated extinction (often called the Ferber method): the caregiver leaves, then returns at planned and gradually longer intervals to offer brief reassurance without picking the baby up. Some guides give example intervals of a few minutes that grow over time, but the exact plan varies.
• Other gentler approaches that are sometimes lumped in, such as staying in the room, gradually moving out, or moving bedtime later and then earlier.

Many people who say they “did CIO” actually did a graduated version, and many critics are describing the full version. It helps to be clear which one is being discussed.

CIO or Ferber: which is better?

There is no approach that is best for every family. Graduated methods such as Ferber’s include check-ins, which some parents find easier emotionally. Full extinction involves fewer interruptions but can be harder for some parents to carry out. Some research comparing different behavioural methods has found improvements in sleep with each of them, rather than one clear winner, though studies are small and varied.

What tends to matter more is whether the approach fits your baby’s age and health, your values, and your ability to stay consistent. Your pediatrician can talk through the options with you.

Is it okay to let a newborn cry it out?

Newborns are not generally considered ready for any form of sleep training. They wake often because they need to feed, and they cannot yet go long stretches without care. Responding to a newborn’s cries, feeding and comforting them is part of normal care and does not “spoil” them.

Pediatric sleep sources commonly suggest waiting until a baby is at least around four to six months old before trying any formal sleep training, and even then, your pediatrician should confirm that your baby is healthy and growing well enough. Ask them what is right for your own child, especially for premature babies or babies with reflux, breathing issues or other health needs.

How long should a baby cry?

This is one of the most common questions, and honest advice is that there is no single number that is right for every baby or every family. How long a baby cries varies widely, and different methods set different limits. Some parents find crying lasts a short time on the first nights, while others find it takes longer.

Some key points:

• If you are using a plan, follow the plan from a source you trust, and agree it in advance with your co-parent.
• Check on your baby if something seems wrong: fever, vomiting, an unusual cry, signs of illness, or a feeling that this is not just protest.
• You are always allowed to stop. If it feels wrong for you or your baby, stopping does not mean you failed.

Safe sleep rules still apply: back to sleep, firm flat surface, nothing soft in the sleep space, and a room set up as your pediatrician advises. The American Academy of Pediatrics advises that babies sleep on their back on a firm, flat surface, in the same room as their parents but not in the same bed, for at least the first 6 months.

What the research does and doesn’t show

Reading about CIO can leave you with the impression that the science is settled, in one direction or the other. In reality, it is more complicated.

Arguments against. Critics point out that crying raises stress hormones and that babies rely on caregivers to calm them. Some writers describe CIO as potentially traumatic for infants, and argue that the long-term effects are unknown. One study often cited measured cortisol, a stress hormone, in babies and found it could stay raised after crying stopped, though this does not tell us what it means for later life.

Arguments for. Supporters point to randomized trials in which babies who received a behavioural sleep intervention slept better, with no measured harm to parent-child attachment, behaviour or stress in the short term. One randomized trial in Australia (Price and colleagues, Pediatrics, 2012) followed families for five years after nurse-led sleep advice and reported no lasting differences, good or bad, between children whose families had received sleep training and those who had not. Parents in these studies also tended to be less tired and, in some cases, less depressed.

Limits on both sides. Some arguments against CIO draw on research about colic, abuse, or animal studies, which do not directly examine modern sleep training, so they may not transfer cleanly. On the other hand, studies of sleep training are small or rely on parent reports, can’t perfectly control for differences between families, and may not capture how every baby feels. Experts such as researcher Gwen Dewar have noted that important questions remain open.

A fair summary might be: current evidence has not shown clear long-term harm from behavioural sleep training in the studies done, but the studies are limited, and the experience of listening to a baby cry is very hard for many families. Both statements can be true at once.

Why parents disagree, and why it is understandable

Sleep deprivation affects mood, health and safety, including the safety of driving or caring for a baby when exhausted. Some parents see sleep training as a way to protect the whole family. Others see responsiveness at night as a core value and feel uncomfortable with any method that involves letting a baby cry alone. Neither group is trying to harm their child.

You are likely to hear strong opinions from relatives, friends and online groups. Try to treat them as opinions, not instructions. You know your baby best.

Before you try any sleep training

A short checklist:

1. Check with your pediatrician that your baby is old enough and healthy enough.
2. Rule out hunger, illness, teething pain or discomfort that might need attention.
3. Set up a safe sleep space and a predictable bedtime routine.
4. Agree on the plan with your partner or co-parent so you respond consistently, and plan how you will support each other. Disagreements about sleep are common; see married couples’ parenting challenges for ways to talk them through.
5. Choose a time when your family is not in the middle of major changes, such as travel, a move or illness.
6. Decide in advance when you would stop or seek advice.

Gentler options

If CIO does not feel right to you, there are other approaches, which families sometimes combine:

• A calming, consistent bedtime routine.
• Putting the baby down drowsy but awake, when you can.
• “Camping out,” where a parent stays nearby and gradually moves further away.
• Short, regular check-ins with a soothing voice or touch.
• Adjusting nap timing and bedtime based on your baby’s cues.
• Accepting that waking at night is normal at many ages and focusing on rest for yourself, such as taking turns with a partner.

These approaches may take longer, and results vary. Some families find the gradual pace easier to live with.

If you have already tried it, or feel guilty

Many parents try something, then feel doubt. If you used a method that now feels wrong, you are not a bad parent, and parenting mantras for self-compassion and repair may help. Babies are generally resilient when they are loved, fed and cared for in the day, and a lot of parenting involves adjusting as you learn. Continuing to be warm and responsive is what matters most. If you are worried about your child’s wellbeing or your own, speak with your pediatrician.

Sleep training and twins

Twins can make sleep feel even more of a puzzle because one baby’s crying can wake the other. Some families sleep train the babies together, others separately, and some choose to wait. Whichever you choose, keep each baby in their own safe sleep space and speak with your pediatrician first. Our article on tips on raising twins covers routines and safe sleep for two babies.

Frequently asked questions

Does CIO damage attachment? Studies that have measured attachment after behavioural sleep training have not generally found harm, but research is limited and opinions differ. Staying warm and responsive during the day is considered important in any case.

Can I stop partway? Yes. You can stop, pause or switch to a gentler method at any time.

What if my baby is sick? Put sleep training on hold, comfort your baby and call your pediatrician if you have any concerns.

When should I get help? If sleep problems continue, if you feel unable to cope, or if you are very low or anxious, talk to your pediatrician or doctor. Support is available.