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A Self-Reg Science Byte
Featured Image: Illustration by Kirsten Wiens, from Applied Self-Reg for Education Systems (Wiens & Hopkins, 2025), available through the Self-Reg Shop.
Why children can seem like completely different people from one day to the next.
Yesterday, your child couldn’t wait to tell you about their day.
They chatted all the way home, remembered to feed the dog without being asked, and proudly showed you the Lego creation they’d spent an hour building. They solved problems, laughed easily, and moved through the evening with confidence.
Today is different.
Their socks feel “wrong.” They can’t find their lunch bag. A simple request is met with tears. Their younger sibling hums a tune, and suddenly everyone is upset.
It’s easy to wonder what changed.
Sometimes the answer is obvious. They’re coming down with a virus. They didn’t sleep well. Something happened at school.
But sometimes there isn’t an obvious answer.
Why Children Can Seem So Different
One of the central ideas in Self-Reg is that children do not bring the same brain-body state to every moment. The nervous system is constantly responding to changing demands, adjusting how energy is used throughout the day. Those changes influence how much capacity is available for thinking, learning, remembering, solving problems, paying attention, connecting with others, and managing the countless demands of everyday life.
Understanding Stress Load
Every experience places demands on the brain and body. Hunger. Bright lights. A noisy classroom. Learning something new. Recovering from illness. Working through disappointment. Trying to fit in with peers. Excitement before a birthday party. Even joyful experiences require energy.
These demands accumulate into what Self-Reg calls a stress load.
As that load grows, the brain begins making biological trade-offs. More energy is directed toward managing the demands of the moment, leaving fewer resources available for flexible thinking, working memory, planning, perspective-taking, and putting the brakes on an impulse. The child hasn’t lost these capacities. They have simply become harder to access because the brain is adapting to a heavier overall load.
Looking Beneath the Behaviour
This helps explain why a child may struggle today with something they managed easily yesterday.
It also helps explain why behaviour can change so quickly.
From a Self-Reg perspective, behaviour is not the beginning of the story. It is the visible expression of what is happening beneath the surface. By the time we notice arguing, withdrawing, forgetting, refusing, or melting down, the nervous system has already been responding to an accumulation of stressors, many of which may be completely invisible to us.
Asking a Different Question
This is why Self-Reg begins with a different question:
Why? Why now?
Not because behaviour doesn’t matter, but because understanding the conditions that gave rise to the behaviour tells us far more than the behaviour alone ever can.
Yesterday’s child didn’t disappear.
Their brain-body state changed.
And when we begin there, we don’t just see behaviour differently.
We begin to see the child differently.
Continue Your Self-Reg Journey
This Science Byte offers just one window into the science behind Self-Reg. If you’d like to explore these ideas more deeply, you’ll find books, self-directed learning, facilitated courses, and practical resources in the Self-Reg Shop.