The trials that set out to measure whether sleep training harms the parent-infant bond did not find harm. They measured it properly, using infant stress hormones and an observational assessment of attachment rather than a questionnaire, and they followed children for years afterwards.
They are also fewer and smaller than the confidence of the public argument suggests, and the honest version of this answer includes that.
What sleep training actually refers to
It is an umbrella term covering several different things, which is part of why the argument about it is so unproductive.
| Method | What it involves | What the trials tested |
|---|---|---|
| Graduated extinction | Returning to settle at gradually increasing intervals | Yes, directly |
| Bedtime fading | Moving bedtime later to match natural sleep onset, then advancing it | Yes, directly |
| Camping out | Staying in the room, withdrawing presence in stages | Studied elsewhere, not in these trials |
| Unmodified extinction | Not returning at all until morning | Rarely tested; not what these trials studied |
Most public argument is conducted about the last row and most research has been done on the first two. Someone defending sleep training and someone attacking it are frequently describing different practices.
The trial that measured the actual worry
The objection that matters is not that a baby cries. It is that repeated unanswered distress raises stress hormones and damages the attachment relationship. That is a specific, testable claim, and Gradisar and colleagues tested it.
Forty-three infants aged 6 to 16 months were randomised to graduated extinction, bedtime fading, or a sleep education control. Sleep was measured by parent diaries and by actigraphy, so not only by parental report. Infant stress was measured through saliva cortisol sampled in the morning and afternoon. Maternal stress was self-reported. Twelve months later, attachment was assessed using the strange situation procedure, alongside child emotional and behavioural problems.
Both interventions improved infant sleep relative to control. There were no adverse cortisol responses, and no effect on attachment or on the children’s emotions and behaviour at follow-up. [gradisar-2016-rct]
That is the right set of measurements. It is also 43 infants, which is the single most important thing to hold on to about this literature.
A schematic of the pattern reported in Gradisar et al. (2016), drawn to show direction and timing rather than measured values.
What happened five years later
The other useful study is longer and larger. Price and colleagues followed up a cluster-randomised trial in which 326 children whose parents reported a sleep problem at seven months received behavioural techniques over one to three consultations at eight to ten months, against usual care.
At age six, 225 families took part, around 69 percent of the original sample. There was no evidence of differences between intervention and control on children’s emotional and conduct behaviour, sleep problems, sleep habits, parent-reported or child-reported psychosocial functioning, or chronic stress. [price-2012-five-year]
Two things about that. Sixty-nine percent follow-up over five years is decent and still leaves a third unaccounted for. And no evidence of a difference is not the same statement as evidence of no difference, though with 225 families it is reasonably informative.
The half that usually goes missing
These trials were not designed to settle an internet argument. The programme they belong to was built around maternal mental health, and Hiscock and colleagues reported that improving infant sleep improved maternal depression symptoms. [hiscock-2007-maternal]
That matters for how the decision is framed. The common framing sets the child’s interests against the parent’s convenience, which assumes the two are separable. A parent who has not slept properly for eight months is not a comfort issue running alongside the child’s wellbeing; it is part of it.
What this evidence does not establish
It does not say you should. It addresses one claim, that these methods harm the child, and finds it unsupported. Deciding what to do with that is a different question and the research does not answer it.
The sample doing the heavy lifting is small. Forty-three infants can rule out a large effect on attachment and cannot rule out a modest one. Anybody citing this as settled, in either direction, is overstating it.
The age range is narrow. Six to sixteen months in one trial, eight to ten months at intervention in the other. None of it transfers to newborns, and the reasoning for a three-month-old is not the same reasoning.
The families had asked for help. Both trials recruited parents who reported a sleep problem and wanted it addressed. That is a different situation from applying a method to a baby whose parents are reluctant, and the trials say nothing about the second.
Both were Australian samples. Infant sleep practices vary enormously between cultures, and so do expectations about what a normal night looks like.
What helps
Rule out the physical causes first. Reflux, allergy, ear infection, sleep apnoea and iron deficiency all produce night waking, and no behavioural method will fix any of them.
Pick the method you can actually run for a fortnight. Consistency does more than the choice between techniques, and an approach abandoned on night three because it felt unbearable has taught the child that persistence works.
Decide in advance what you will do, while you are not exhausted. Three in the morning is the worst possible moment to make a judgement call about your own parenting.
Count your own sleep as data. If you are heading into depression, that is a reason to act rather than a reason to feel guilty about acting. Our guide to depression covers what the early signs look like.
Do not sleep train if you do not want to. Plenty of children sleep through eventually without any of this. The evidence says the methods are not harmful; it does not say the alternative is.
For what attachment actually is, and how little it depends on any single practice, our guide to attachment theory covers the research the word comes from. And our overview of parenting and mental health covers the wider question of which parenting decisions the evidence says actually move outcomes.
When to seek help
Speak to a doctor if your child’s night waking comes with snoring, pauses in breathing, pain, or poor growth, or if it starts suddenly after a period of settled sleep. Speak to a doctor about yourself if low mood, anxiety or hopelessness has lasted more than two weeks, which is common after months of broken sleep and is treatable.
If you are having thoughts of harming yourself or your baby, treat that as urgent and contact your local emergency services or a crisis helpline. Thoughts like that are more common than people are told and they are a reason to get help quickly rather than a reason to be ashamed.
How MyFreud can help
MyFreud tracks your own mood against what your nights actually looked like, which is the measurement most missing from this decision. Parents are asked to weigh their child’s wellbeing against their own and given no way to see what the second is doing. A log makes it visible.
Download MyFreud and start today: App Store or Google Play.