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Stress only harms without recovery
Stress in bursts
A faster heartbeat in the middle of a stressful moment is not a problem to eliminate. Cortisol is normally high at the start of the day to help with waking up, then comes in little bursts as stressful things come up, and the system turns itself off once the stressor is gone, like a spigot closing.
When it never lets up
When stress is incessant, studies find that system gets dysregulated. The cortisol spigot turns on too much, too little, or at the wrong times of day, which can raise the chance of cardiovascular disease, depression, and anxiety. The evidence comes from groups who face stressors day in and day out, such as people caring for someone who is sick or disabled, people who have been abused, people living in low income neighborhoods, and people who experience racism.
Possible warning signs
No sure signal confirms chronic stress, but reviews point to feeling irritable or overwhelmed a lot. Changes in mood, feeling down, and trouble going to sleep are other clues that someone may be heading into chronic stress.
Why is cortisol highest in the morning?
Cortisol follows the body's internal clock, which is set by a small region in the brain called the suprachiasmatic nucleus. Levels climb sharply in the first 30 to 45 minutes after waking, a pattern known as the cortisol awakening response. The rise helps mobilize energy for the day, and levels then drift down through the afternoon and evening. By night cortisol sits near its daily low.
How does the stress system turn itself off?
It runs on negative feedback: cortisol binds to receptors in the brain, including in the hippocampus and hypothalamus, which tell the system to stop releasing more. Under prolonged stress, those receptors can become less sensitive, a state called glucocorticoid resistance. Sheldon Cohen and colleagues at Carnegie Mellon reported in 2012 that people under long-term stress showed reduced sensitivity to cortisol's anti-inflammatory signal. The finding linked chronic stress to inflammation.
Why do caregivers show lasting stress effects?
Caregiving often has no end date, so the stress system gets few chances to switch off. In a 2004 study, Elissa Epel and Elizabeth Blackburn at the University of California, San Francisco found that mothers caring for a chronically ill child had shorter telomeres, the protective caps on chromosomes. The mothers who perceived the most stress had the shortest ones. Telomere length is widely used as a marker of cellular aging.
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