Or when the doorbell goes off at an unexpected hour?
Or when you find yourself walking down a dark, unfamiliar street?
In those moments, something changes instantly inside your body.
Your heart starts racing. Your breath becomes quicker. You feel alert, almost on edge.
This isn’t random. All of these responses are controlled by your autonomic nervous system, which has two main parts- the sympathetic and the parasympathetic nervous systems.
To understand why they exist, we need to go back thousands of years.
Early humans lived in unpredictable environments where danger could appear without warning. When they were out hunting or gathering and sensed a threat, their sympathetic nervous system would activate. This is what we call the ‘fight or flight’ response. It prepared the body to either face the danger or escape from it. Heart rate increased, breathing quickened, peripheral blood flow increased and energy was mobilised.
When they returned to safety, their system would shift. The parasympathetic nervous system would take over. The heart rate would slow down, breathing would settle and the body would move into recovery mode, often referred to as ‘rest and digest’ mode.
These two systems don’t work in isolation. They constantly balance each other, helping the body respond to the moment and then return to a state of ease.
Now fast forward to modern life.
We may not be facing physical danger in the same way, but the body still responds strongly to perceived threats. An unexpected call, email, a difficult conversation, unfamiliar places, uncertainty about the future. Each of these can trigger the same stress response in the body.
Research in neuroscience and stress physiology shows that the brain does not always clearly distinguish between real danger and perceived threat. The result is that the sympathetic nervous system gets activated more often than it needs to.
But here’s the important difference.
In the past, these stress responses were short-lived. Once the danger passed, the body had time to recover.
Today, the activation is often lower in intensity, but far more frequent and prolonged.
So even when there is no immediate danger, the body can remain slightly on edge.
And when this happens repeatedly, without enough time in the parasympathetic state, the system doesn’t fully switch off.
This is why you might lie down to rest but still feel wired.
Your body feels tired but your mind keeps going.
‘Doing nothing’ doesn’t always feel restful.
Over time, this constant low-level activation is associated with a higher risk of several physical and mental health conditions, and it can affect how we sleep, recover and experience everyday life.
So the real question becomes:
If the body is wired to protect us, why does it feel like it’s working against us?
If this response is automatic…can we consciously influence it?
Can we learn to signal safety to the body, rather than stress?
Can we gently guide ourselves back into a state of rest, even in the middle of a busy, modern life?
Because if that is possible, it changes everything.
We will explore that in the next blog.