Does Bed-Sharing Affect Kids' Psychological Development?

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One common question for new parents is this one: "Is s/he a good baby?"

This usually means, "Is your baby content and sleeping well?"

Parents with "good" babies are congratulated, while those with "troublesome" babies get sympathy and advice. As you can imagine, how well a baby sleeps is one of the first things people judge new parents on. So, it’s not a surprise that infant sleep is a big concern and a topic of conversation for many families.

In Western countries, a new industry of "baby sleep coaches/trainers/consultants" has appeared, offering to help parents teach their babies to sleep alone in a crib and stay asleep all night. But this idea of babies sleeping independently and without waking up is not common everywhere in the world and is very different from how babies slept for most of human history.

Parental Bed-Sharing Was Once the Norm

Before the 19th century, new parents in the United Kingdom did not worry much about infant sleep. Families, including mothers and babies, often slept in close contact with each other. This way, if a baby woke up at night, someone was always there to respond quickly.

This changed with the Industrial Revolution in the 1800s. More middle-class families emerged, and independence became more important. Longer work hours made uninterrupted sleep more desirable, and more parents started living away from their extended family. Today, parenting advice often stresses strict sleep schedules and having babies sleep alone to promote independence. However, it is important to remember that this was not always the norm and still is not in many parts of the world.

The Bed-Sharing Controversy

Bed-sharing remains a controversial but common parenting practice. Some experts warn against it (before 6 months of age) due to its association with sudden infant death syndrome (SIDS), while others argue that it has potential benefits for children’s development (Ball, Hooker, & Kelly, 1999; McKenna & McDade, 2005; Moon et al., 2022). There are many reasons for parents to bed-share, but for some, it’s their only way to manage overtiredness and frequent infant night-waking. (See my previous post for a detailed discussion on the controversy around bed-sharing.)

However, there is little scientific evidence about the psychological effects of bed-sharing on children (Barry & McKenna, 2022). Researchers cannot carry out experiments on this topic by asking one group of parents to bed-share while asking another group not to, because this is a personal parenting choice. To answer this question, the best approach is observational prospective longitudinal studies. These studies follow children over time, recording various measures of their emotional and behavioral development from early childhood through later years.

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Does Bed-Sharing Impact a Baby's Psychological Development?

Answering this question was the aim of my recent research (Bilgin et al., 2024). I used data from the U.K. Millennium Cohort Study, in which 16,599 children were followed up from 9 months of age to 11 years of age. The U.K. Millennium Cohort Study is representative of the U.K. population of individuals born in 2000 to 2002, which includes ethnically and socio-economically diverse participants from England, Wales, Scotland, and Northern Ireland.

Parents reported whether they were bed-sharing with their babies at 9 months. They were also asked to report whether they observed signs of depression and anxiety (called "internalizing symptoms") and aggression and hyperactivity (called "externalizing symptoms") in their children repeatedly at ages 3, 5, 7, and 11.

In this study, we were able to account for the impact of several important variables that might be linked to parental bed-sharing such as maternal psychological distress, parental socioeconomic status, parenting beliefs, breastfeeding, and infant night waking frequency.

We looked at how children's internalizing and externalizing symptoms changed from ages 3 to 11. There were four categories:

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• 56.4 percent had low levels of internalizing and externalizing symptoms that remained low.
• 27.2 percent started with low internalizing symptoms that increased and moderate externalizing symptoms that decreased over time.
• 7.5 percent had moderate levels of both internalizing and externalizing symptoms that decreased over time.
• 8.9 percent had severe and chronic symptoms: initially low internalizing symptoms that increased and high levels of externalizing symptoms that remained stable over time.

There were no links between bed-sharing at 9 months and the trajectories of internalizing or externalizing symptoms in childhood. Other characteristics that are linked to bed-sharing such as low parental education and maternal psychological distress were associated with these symptom trajectories. Thus, the likelihood of belonging in internalizing and externalizing symptom trajectories is explained by other factors related to bed-sharing rather than bed-sharing itself.

This finding is reassuring for parents who worry about how bed-sharing might affect their child's psychological development. Further, it aligns with our previous research, which found that bed-sharing does not impact the formation of secure infant-mother attachment (Bilgin & Wolke, 2022).

Bottom Line

It’s important to recognize that bed-sharing might be the preferred choice for some parents for various reasons. They can be reassured that, as long as safety measures are followed, bed-sharing is unlikely to impact a child’s emotional and behavioural development.

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