There is no single “correct” duration for letting a baby cry it out, because the answer depends on which method you’re using and how old your baby is. Most approaches recommend letting a baby cry for somewhere between 3 and 20 minutes before you check in, with that window gradually increasing over the course of a week. Babies are generally ready to start at around 4 months old, and most see significant improvement within three to seven nights.
When Babies Are Ready for Sleep Training
Four months is the earliest most pediatricians recommend starting any form of cry it out. Before that age, babies’ sleep cycles haven’t matured enough, their circadian rhythm isn’t established, and they genuinely need multiple nighttime feedings. At 4 months, most babies are developmentally capable of learning to self-soothe and may no longer require overnight feeds, though many still do.
Feeding needs vary by age and whether your baby is breastfed or formula-fed. Between 3 and 4 months, breastfed babies typically still need three to four feedings per night, while formula-fed babies need two to three. By 5 to 6 months, that drops to one to three for breastfed babies and one to two for formula-fed babies. Sleep training should never mean withholding food from a hungry baby. If your baby still needs nighttime calories, you can still sleep train by feeding when genuinely needed and letting them self-soothe back to sleep afterward.
Graduated Check-In Method (Ferber)
The most widely known approach is the graduated extinction method, often called the Ferber method. You put your baby down drowsy but awake, then wait a set number of minutes before briefly checking in. Each check-in is short (a minute or two of verbal reassurance, a pat on the back) and the intervals get longer as the night and week progress.
On the first night, you wait 3 minutes before your first check, then 5 minutes before the second, then 10 minutes between all remaining checks. By night three, you’re starting at 10 minutes and stretching to 15. By night seven, the first wait is 20 minutes and the longest gap between checks is 30 minutes. The idea is that your baby gradually learns to fall asleep during those waiting periods, and the check-ins reassure both of you that everything is fine.
These intervals aren’t rigid rules. Richard Ferber himself notes that parents can modify the timing to fit their comfort level. Some parents shorten every interval by a few minutes, especially on the first night. What matters more than the exact numbers is the pattern: start short, get longer, stay consistent.
Full Extinction (No Check-Ins)
Full extinction, sometimes called “unmodified” cry it out, is more straightforward. You put your baby in the crib, say goodnight, and don’t return until morning (or until a feeding is needed). There are no timed check-ins.
Some versions of this approach suggest expecting 10 to 20 minutes of crying before sleep, particularly for babies 8 months and older. In practice, the first night can involve significantly more crying than that. Research comparing the two extinction methods found no significant difference in how quickly they worked or how difficult parents found them. Both produced longer, more consolidated nighttime sleep compared to gentler methods like staying in the room. The tradeoff is that full extinction can feel harder emotionally for parents, even if the total amount of crying over the full training period is sometimes less because there are no check-ins to restart the cycle.
How Many Nights It Takes
A 2018 study tracking real-world sleep training found that crying peaked on the first night and resolved within a week. Most sleep specialists say you should see clear improvement by the end of seven days, with training typically complete within two weeks. If you’re not seeing any progress after a week, it’s worth pausing and reassessing rather than pushing through. Your baby may not be ready, or something else (illness, a developmental leap, hunger) may be interfering.
The first one to three nights are almost always the hardest. Many parents report that their baby cries for 45 minutes to over an hour on night one, then 20 to 30 minutes on night two, dropping sharply from there. By nights four or five, many babies fuss for under 10 minutes before falling asleep.
Is It Safe for Your Baby?
The most common concern parents have is whether prolonged crying causes lasting stress or damages the bond with their child. A study conducted through the American Academy of Pediatrics measured cortisol (the body’s primary stress hormone) in babies who went through sleep training and babies who didn’t. By the end of training, the sleep-trained babies actually had lower cortisol levels. The study also found no difference in attachment style or behavioral problems between the two groups.
The AAP’s own guidance supports letting babies learn to fall asleep independently, advising parents not to rush in when a baby cries at night and noting that a 6-month-old who wakes and cries for a few minutes will often go back to sleep on their own.
When to Intervene During a Session
Cry it out doesn’t mean ignoring your baby no matter what. There are specific signals that should prompt you to go in and check, regardless of where you are in the schedule.
- A change in pitch or intensity. If your baby’s cry suddenly sounds different from their usual protest cry, or shifts to shrieking, go check. Crying is their only way to communicate, and a dramatic change can signal pain, a limb caught in the crib, or vomiting.
- Crying that drags on well past what’s expected. If you’re on night five and your baby is still crying for an hour, something isn’t working. Reset and try again the next night, or take a break from training for a few days.
- Illness or teething. If your baby is sick, running a fever, or cutting teeth, pause sleep training. Their crying is telling you something real.
Trust your instincts on this. If something feels wrong, checking on your baby won’t ruin your progress. A single disruption in the schedule is far less significant than missing a genuine need.
Picking the Right Approach
If you want structure and the reassurance of regular check-ins, graduated extinction gives you a clear nightly plan. If you find that your check-ins seem to agitate your baby more (some babies get more upset seeing a parent and then watching them leave again), full extinction may actually involve less total distress. Neither method has been shown to work faster than the other in research settings, so the best choice is the one you can stick with consistently for a full week.
Consistency matters more than which method you pick. Switching approaches mid-week, or doing cry it out some nights but not others, tends to extend the process and increase total crying. Whatever you choose, commit to at least five to seven nights before evaluating whether it’s working.