What the Marshmallow Test Can Teach Us About Sleep Training

You’ve probably heard of the famous marshmallow test—a psychological experiment where young children were offered one marshmallow immediately, or two if they could wait. For years, it was seen as a test of willpower and future success.

But new research is shifting the spotlight away from willpower alone and toward something much deeper: trust.

And it turns out, this has a lot to teach us about sleep training too.

The New Take on the Marshmallow Test

In recent years, researchers revisited the marshmallow study and uncovered a fascinating insight: many children who waited for the second marshmallow weren’t necessarily better at resisting temptation. They simply trusted that the adult would return and follow through on the promise.

In other words, delay of gratification was strongly linked to the child’s belief in the reliability of their caregiver.

This finding reframes the whole conversation. It's not just about internal discipline—it’s about secure relationships and the ability to rely on others.

So What Does This Have to Do With Sleep Training?

Quite a lot, actually.

When it comes to sleep, children—especially babies and toddlers—are navigating big emotions and physical needs at bedtime. Whether they’re learning to fall asleep independently or managing night wakings, their emotional security and trust in you as their caregiver play a huge role.

Here’s how the marshmallow test findings map beautifully onto sleep training:

1. Trust is the Foundation for Sleep Skills

Just like the children who waited for the second marshmallow, babies and young children need to trust that:

• Their caregivers are consistent and responsive.

• Their needs will be met—even if not immediately.

• The world around them is safe and predictable.

Sleep training that’s grounded in responsiveness and routine helps build that trust. It’s not about withdrawing support—it’s about showing your child that sleep is safe, and that you’re still there, even if you're not always right beside them.

2. Consistency Builds Confidence

In the updated marshmallow study, children who had previously experienced unreliable adults (who didn’t return with the second marshmallow) were much more likely to eat the first one right away.

Similarly, when bedtime routines are inconsistent, or responses to night wakings vary dramatically, children can feel uncertain about what’s coming next. This can make it harder for them to relax and settle to sleep.

Consistent, predictable sleep routines provide a clear, safe structure—helping your child feel secure and able to let go into sleep.

3. Independence is Grown, Not Forced

Self-soothing at bedtime isn’t about toughing it out. It’s a skill that blossoms when a child feels safe and secure. The ability to manage feelings around bedtime grows from the foundation of a strong parent-child bond.

Just like in the marshmallow test, self-regulation and independence emerge from trust—not pressure.

The Bottom Line?

Sleep training works best when it’s not just about teaching a skill, but about strengthening your child’s sense of safety, security, and connection. When children trust that their needs will be met and their world is predictable, they feel more able to explore independence—including the ability to fall asleep on their own.

So the next time you hear about the marshmallow test, remember: it’s not about testing willpower. It’s about relationships. And that’s the same heart behind sleep support.