Sleep training teaches your baby to fall asleep independently, without being rocked, fed, or held to sleep. Most babies are ready to start around 4 to 6 months old, when their internal body clock matures enough to support longer stretches of nighttime sleep. The process typically involves choosing a method, setting up the right sleep environment, and staying consistent for one to three weeks until your baby learns to self-soothe at bedtime.
When Your Baby Is Ready
Newborns can’t be sleep trained. Their sleep cycles are too short, they need frequent feedings, and their brains haven’t yet developed the ability to self-soothe. The earliest most families can start is around 4 months, though some babies do better closer to 6 months.
The reason for this window is biological. Your baby’s pineal gland, which produces the sleep hormone melatonin, isn’t capable of rhythmic production until roughly 3 to 4 months of age. Before that point, babies simply don’t have a functioning internal clock telling them to sleep at night and stay awake during the day. Stable nighttime sleep patterns, measured by body movement and motor rest, typically emerge between 3 and 6 months. By 9 to 12 months, nighttime melatonin production is five to six times higher than it was at 6 weeks.
Signs your individual baby may be ready: they’re at least 4 months old, they can go longer stretches without eating, and their pediatrician hasn’t flagged any weight or feeding concerns that would require overnight calories.
Setting Up the Sleep Environment
Before you pick a method, get the room right. Keep the temperature between 68 and 72°F (20 to 22°C). Using a fan in the room can help with air circulation and has been associated with a lower risk of SIDS. Make the room as dark as possible with blackout curtains, and consider a white noise machine set at a consistent, moderate volume to mask household sounds.
Put your baby down when they’re showing sleepy cues but not fully asleep. Watch for yawning, eye rubbing, ear tugging, or turning away from faces and toys. Catching this window matters because an overtired baby actually has a harder time falling asleep.
The Graduated Check-In Method (Ferber)
This is probably the most widely recognized approach. You put your baby down awake, leave the room, and wait a set number of minutes before briefly checking in. During check-ins, you can offer a few words of comfort or a quick pat, but you don’t pick the baby up or feed them back to sleep.
On the first night, you wait 3 minutes before your first check-in, then extend the interval with each subsequent check. The second night starts at 5 minutes. Each following night, you stretch the initial wait a bit longer. The intervals grow gradually over the course of about a week. Most babies begin falling asleep faster within 3 to 5 nights, though full adjustment can take longer.
This method works well for parents who want a structured plan but aren’t comfortable leaving their baby without any reassurance. The key is keeping check-ins brief and boring. If your visits become stimulating or you start picking the baby up, the intervals lose their purpose.
Full Extinction (Cry It Out)
With this approach, you put your baby down awake and don’t return until morning (or a scheduled feeding time). There are no check-ins. It’s straightforward but emotionally difficult for many parents.
Crying often gets worse before it gets better. Research on this method found that baseline crying of 35 to 40 minutes per night increased to over 70 minutes during the first two nights of training. One study found it took 3 or more weeks for nighttime wakings and crying to drop below 4 episodes per week. Not all babies respond within a few nights, which can be discouraging if you expected faster results.
This method is sometimes chosen by parents who’ve tried gentler approaches without success, or whose own check-in visits seem to escalate their baby’s distress rather than ease it.
The Chair Method
If a no-contact method feels like too much, the chair method lets you stay in the room. You place a chair next to the crib and sit there while your baby falls asleep. You don’t pick them up, but your presence provides reassurance. Every few nights, you move the chair a little farther from the crib, toward the door, then outside the door, and eventually out of sight entirely.
This is slower than the other methods and requires patience, since you’ll be sitting quietly in a dim room for stretches of time. Some babies also find a parent’s visible presence more frustrating than comforting, especially if they can see you but you won’t pick them up. It’s worth trying for a few nights to see how your baby responds before committing or switching.
Does Sleep Training Harm Your Baby?
This is the question most parents are really asking when they search for sleep training information. Multiple studies have measured cortisol, the body’s primary stress hormone, in babies during and after sleep training. The results are largely reassuring.
Two separate studies that measured cortisol the morning after sleep training and one week after found no elevated stress levels in the babies. One study that measured cortisol 40 minutes into the bedtime stressor found comparable levels between babies who cried alone and babies given a more responsive bedtime interaction. The researchers concluded that a crying infant left alone showed similar stress levels to a baby given reduced bedtime interaction like not being rocked or fed to sleep.
Only one study, by Middlemiss in 2012, found prolonged and elevated cortisol at the moment of separation during an extinction protocol. A follow-up study by the same researcher in 2017 found no cortisol elevation when babies were actively responding and settling during the intervention. The overall picture from the research is that sleep training does not appear to cause lasting physiological stress, though individual nights can certainly be stressful for both baby and parent.
Night Feedings and Sleep Training
Sleep training and night weaning are two separate things, and you don’t have to do both at the same time. Many families sleep train first (teaching the baby to fall asleep independently at bedtime) while keeping one or two scheduled night feeds.
Formula-fed babies often no longer need nighttime calories after 6 months. For breastfed babies, the recommended age for night weaning is 12 months, since most children are getting enough daytime nutrition by then. If your baby is taking less than 60 ml (about 2 ounces) during a night feed, that feed is likely more habit than hunger, and you can consider dropping it.
A practical approach: if your baby wakes at a time you’ve designated as a feeding time, feed them. If they wake at other times, use your chosen sleep training method to help them resettle. This way you’re not withholding nutrition while still teaching independent sleep skills.
Handling Setbacks
Illness, teething, travel, and developmental leaps can all disrupt sleep training progress. This is normal and doesn’t mean the training failed.
During teething, you may need to check on your baby more frequently and take a gentler approach. If they’re in significant pain, it’s reasonable to pause training entirely for 2 to 3 days per tooth and restart once the worst has passed. Illness is similar: comfort your baby as needed while they’re sick, then return to your method once they’ve recovered. Most babies pick up where they left off faster than the initial training took.
Delay night weaning during active teething or sleep regressions, since night feeds can provide comfort when your baby needs it most. Once sleep patterns stabilize again, you can resume reducing feeds gradually. If disrupted sleep persists for more than 6 weeks or you notice your child’s development slowing, that’s worth bringing up with your pediatrician.
Choosing the Right Method
There’s no single best method. The best one is the one you can stick with consistently. A graduated approach done with total consistency will outperform a stricter method you abandon after two nights. Consider your own temperament honestly: if you know you can’t listen to prolonged crying without intervening, start with the chair method or graduated check-ins rather than setting yourself up to break protocol with full extinction.
Whatever you choose, consistency is the non-negotiable ingredient. Responding differently each night, sometimes picking the baby up and sometimes not, teaches your baby that crying long enough will eventually change the outcome. Commit to your chosen approach for at least a full week before evaluating whether it’s working. If both parents or caregivers are involved in bedtime, make sure everyone is following the same plan.