Cry It Out Method: Does It Cause Damage? What Research Actually Says
A 2016 Pediatrics study found no difference in stress hormones or attachment. What CIO actually involves and night-by-night expectations.
🧠 What the Cry It Out Method Actually Is
The cry it out method — also called extinction or full extinction — means placing your baby in their crib fully awake at bedtime, saying goodnight, leaving the room, and not returning until either a scheduled night feed or morning. That's it. You don't stand outside the door shushing. You don't peek in. You let your baby figure out how to fall asleep without your help.
This is not the same as ignoring your baby all day or withholding comfort when they're sick. CIO is specifically about the moment of falling asleep. During the day and at non-sleep times, you respond to your baby normally. The goal is to remove the "sleep crutch" — whether that's nursing, rocking, bouncing, or holding — so your baby learns to transition from awake to asleep independently.
The term "cry it out" sounds harsh, and it's the reason this method is so controversial. But what you're actually teaching your baby is a skill: the ability to fall asleep on their own. Every human wakes briefly between sleep cycles (adults do too — we just don't remember). A baby who can only fall asleep while being rocked will cry for rocking every time they surface between cycles, which can mean 4 to 8 wakings per night.
📋 Before You Start: Prerequisites
CIO is not appropriate for every baby or every situation. Before starting, make sure all of the following are true:
- Age: Your baby is at least 4 months old (adjusted age if premature). Before this, babies lack the neurological capacity to self-soothe.
- Weight: Your baby weighs at least 14 pounds and your pediatrician confirms they can go longer stretches without feeding.
- Health: No active illness, ear infection, reflux flare-up, or teething pain. Address medical issues first.
- Environment: The room is dark (blackout curtains), cool (68-72°F), and has continuous white noise. The crib meets safe sleep standards — firm mattress, fitted sheet, nothing else.
- Routine: You have a consistent bedtime routine already in place for at least a few days.
- Both parents are on board. If one parent is going to "rescue" the baby after 10 minutes, the method won't work and you'll just extend the crying over weeks instead of days.
📅 Night-by-Night: What to Expect
Here's what the first week typically looks like. Every baby is different, but this pattern holds for the majority:
- Night 1: The hardest night. Expect 45 to 60 minutes of crying, sometimes longer. Some babies cry for 90 minutes. This is normal. Your baby is confused and protesting the change, not in danger. Many parents sit outside the room, watch on the monitor, or leave the house entirely (with a partner monitoring).
- Night 2: Often similar to night 1, sometimes slightly less. Some babies actually cry more on night 2. Don't panic — this doesn't mean it's not working.
- Night 3-4: You may see an "extinction burst" — a temporary increase in crying intensity. This is actually a sign the method is working. Your baby is making one last strong effort before accepting the new routine. Crying typically drops to 20-30 minutes.
- Night 5-7: Most babies are crying for under 10 minutes, and many go down with little or no fussing. Night wakings have also decreased significantly.
For nighttime wakings: if your pediatrician says your baby still needs one night feed, decide on a time (e.g., any waking after midnight) and feed at that waking only. For all other wakings, treat them the same as bedtime — don't go in.
🔬 What the Research Says About Cortisol and Attachment
The biggest fear parents have is that CIO causes lasting emotional harm. Here's what the actual studies found:
- The 2016 Gradisar study (Pediatrics): Researchers measured salivary cortisol in 43 infants undergoing graduated extinction vs. a control group. At 12 months, there were no differences in cortisol levels, parent-child attachment (measured by the Strange Situation test), or behavioral/emotional problems.
- The 2012 Price et al. study (Pediatrics): A large Australian trial followed 326 families for 5 years after sleep training. At age 6, children who had been sleep trained showed no differences in emotional health, behavior, sleep quality, stress, or parent-child closeness compared to controls.
- The 2006 Mindell meta-analysis: Reviewed 52 studies on behavioral sleep interventions and concluded that extinction-based methods are effective and produce no evidence of adverse effects.
One widely-cited 2012 study by Middlemiss measured cortisol in babies during sleep training and found that on the first day, babies' cortisol remained elevated even after they stopped crying. Critics point to this as evidence of hidden stress. However, this study had only 25 participants, measured cortisol on the first day only, and didn't follow up long-term. By the time babies learn to fall asleep quickly (typically by day 3-5), the brief period of fussing produces no measurable cortisol spike.
⚖️ CIO vs. Ferber: Which Approach to Choose
Dr. Marc Weissbluth (author of "Healthy Sleep Habits, Happy Child") advocates for full extinction — leave the room and don't return. His reasoning: check-ins can actually make crying worse because the baby gets re-stimulated each time a parent appears and then leaves again. It's like waving a cookie in front of a toddler and taking it away repeatedly.
Dr. Richard Ferber (author of "Solve Your Child's Sleep Problems") recommends graduated extinction — timed check-ins at increasing intervals. A typical Ferber schedule for night 1: check at 3 minutes, then 5, then 10, then 10 minutes for the rest of the night. Night 2: 5, 10, 12. Night 3: 10, 12, 15. During checks, you briefly pat the baby or offer verbal reassurance (30-60 seconds), then leave again. You do not pick the baby up.
- Full extinction may work faster (3-5 nights vs. 5-7 for Ferber) because there's no intermittent reinforcement of crying.
- Ferber can feel more manageable for parents who need reassurance that their baby is okay. The checks are for the parent's comfort, not the baby's — some babies actually get angrier after checks.
- If Ferber checks are escalating the crying, consider switching to full extinction. There's no rule that says you must do one or the other exclusively.
🚫 When NOT to Use Cry It Out
CIO is not the right choice in these situations:
- Under 4 months old: Babies this young cannot self-soothe and may still need frequent night feedings for growth.
- Premature babies: Use adjusted age. A baby born 2 months early should not start CIO until 6 months chronological (4 months adjusted).
- Medical issues: Reflux, ear infections, respiratory illness, fever, or any condition causing pain. Treat the medical problem first.
- Failure to thrive or poor weight gain: These babies may genuinely need every night feed. Work with your pediatrician.
- Recent major disruption: Moving to a new home, starting daycare, a new sibling, or travel. Wait until life is stable for at least 2 weeks.
- Parent mental health concerns: If listening to crying triggers severe anxiety, panic attacks, or worsens postpartum depression, this method may not be right for you. Gentle methods exist and also work — they just take longer.
🔄 Alternatives to Full Extinction
If CIO doesn't feel right for your family, these methods also teach independent sleep:
- Graduated extinction (Ferber): Timed check-ins at increasing intervals. Less abrupt but takes slightly longer.
- Chair method: Sit in a chair next to the crib. Every 2-3 nights, move the chair farther away until you're out of the room. Takes 1-2 weeks.
- Pick Up Put Down (Tracey Hogg): Pick baby up when they cry, put them down the moment they stop. Repeat as many times as needed. Can take 2-4 weeks.
- Fading: Gradually reduce your level of intervention (e.g., rocking to patting to shushing to presence only). Takes 2-4 weeks.
All methods that teach independent sleep skills work. The "best" method is the one you can do consistently. Inconsistency — trying CIO for one night, then co-sleeping, then trying Ferber — is the one approach that reliably fails.