Sleep isn’t simply a matter of feeling tired and closing your eyes—it’s a highly coordinated biological shift. The body must move from a state of alertness into a state of deep restoration, and that transition is controlled largely by two branches of your autonomic nervous system: the sympathetic and the parasympathetic.
Think of them as the body’s accelerator and brake. Both are essential. Both influence sleep. And both can work for—or against—you depending on your daily habits and stress levels.
In this post, we’ll break down what these systems do, how they interact during the sleep–wake cycle, and how you can support the parasympathetic system to promote deeper, more restorative rest.
