Safe relationships are a biological requirement for health. From birth onward, the human nervous system develops in response to safe, attuned connection—through touch, facial expression, tone of voice, and emotional availability. These cues shape how the brain, immune system, gut, and stress response learn to regulate themselves across the lifespan. This is known as co-regulation. Humans are wired to help regulate one another’s nervous systems through safe connection. When safety is present, the body can relax and direct energy toward digestion, immune balance, detoxification, and repair. When safety is missing, or when relationships are chronically stressful, the nervous system remains on guard, disrupting digestion, immunity, hormonal signaling, and inflammatory regulation over time.