Ever wondered what causes the nervous feeling in your stomach?

Chris Smith Naked scientist explains that butterflies are part of the body’s fight-or-flight reaction when there’s a threat or you are excited.

He says it is part of your nervous system over which you have no control.

When we anticipate danger, threat or excitement, this autonomic system kicks in and specifically one part of it called the sympathetic nervous system.— Chris Smith, Naked Scientist

This has a number of effects, one of them is it makes your heart beat faster. It also has the effect of shutting off your intestines. So part of the butterflies and the sinking sensation in the stomach that we describe, is the sympathetic nervous system deactivating your guts and all the muscles relaxing and your stomach relaxing and everything stopping – that is part of what we describe as butterflies in our stomach.— Chris Smith, Naked Scientist