What Is CIO?
CIO is the abbreviation for "cry it out," a sleep training method where parents allow a child to cry during bedtime or after nighttime awakenings without immediately responding. The goal is to help children learn to self-soothe and fall asleep independently, typically used for infants and toddlers between 6 months and 3 years old.
This method operates on the principle that repeated parental intervention reinforces nighttime crying behavior. By reducing that response, proponents argue children eventually learn to settle themselves. However, CIO exists on a spectrum. Some approaches involve complete non-intervention (full extinction), while others combine waiting periods with periodic parent check-ins (graduated extinction).
Research and Evidence
Studies on CIO show mixed results depending on the specific method and how long it's applied. A 2012 study in Pediatrics found that extinction-based sleep training reduced infant crying within 3 to 7 nights for roughly 50% of families. However, the same research showed no significant difference in long-term sleep outcomes between CIO and gentler methods like scheduled awakenings by 6 months post-intervention.
Concerns raised by sleep specialists include potential stress hormone elevation in infants and the risk of reinforcing avoidant patterns if applied inconsistently. The American Academy of Pediatrics does not recommend CIO as a first-line approach for normal infant sleep development, instead endorsing sleep hygiene practices, consistent bedtime routines, and graduated extinction as safer alternatives.
When CIO Is Considered
- Persistent sleep onset insomnia in children aged 6 months to 3 years despite standard sleep hygiene
- Frequent nighttime awakenings unrelated to hunger, pain, or medical conditions like sleep apnea
- Parental exhaustion affecting family functioning
- Ruling out underlying sleep disorders through polysomnography or clinical evaluation when daytime symptoms suggest apnea or other conditions
Alternative Approaches
Sleep medicine professionals increasingly recommend methods aligned with circadian rhythm principles and cognitive behavioral therapy for insomnia (CBT-I) concepts, even for young children. These include:
- Graduated extinction: Parent checks occur at increasing intervals (5, 10, 15 minutes) rather than immediate response or complete absence
- Full extinction: Complete non-intervention until morning, typically used only when medical causes are ruled out
- Sleep hygiene optimization: Consistent sleep and wake times supporting natural circadian rhythm, appropriate room temperature (65-68 degrees Fahrenheit), and light exposure management
- Scheduled awakenings: Parent wakes child before typical crying episodes occur, gradually extending intervals
Common Questions
- Is CIO harmful to infant development? Current evidence suggests CIO does not impair attachment or long-term emotional development when used after 6 months and in otherwise healthy infants. However, it carries higher distress for both child and parent compared to graduated approaches. Consultation with a pediatric sleep specialist is recommended before starting any sleep training.
- How long does CIO typically take to work? Response varies widely. Some families see reduced crying within 3 to 5 nights, while others experience 2 to 3 weeks of continued nighttime waking. Inconsistent application often extends the timeline and may worsen initial protests.
- Should I try CIO if my child has sleep apnea? No. Medical conditions like sleep apnea require polysomnography diagnosis and treatment before any behavioral sleep training. CIO is inappropriate when underlying medical sleep disorders are present.