THE BALLAST PRINCIPLE

Plain-language definitions

Glossary

Cortisol
The body’s main stress hormone, released by the adrenal glands.
Sleep debt
The running total of sleep you’ve missed versus what you need.
Rumination
Repetitive, circular thinking that produces distress but no resolution.
Vagus nerve
The main nerve of the body’s “rest and digest” calming system.
Allostatic load
The cumulative wear-and-tear of repeated stress on the body.