Stress & your brain

Stress is usually a reaction to something happening, like homework or a work problem. Anxiety can continue even when there is no clear threat, and becomes a concern when it lasts and gets in the way of daily life.

Some stress can help, like giving you the energy to meet a deadline. For children, brief, mild stress is a normal part of healthy development when caring adults are there to help.

Experts describe some stress as “tolerable.” It is more serious and lasts longer, like a loss or a frightening event. With supportive relationships, the brain and body can recover.

When hardship is strong, frequent and long-lasting, and there isn’t enough support, the stress response can stay switched on. Experts call this “toxic stress,” especially in children.

The sympathetic nervous system works like a gas pedal. It raises heart rate and blood pressure, opens the airways and releases stored sugar and fat for quick energy.

The parasympathetic nervous system works like a brake. Once danger passes, it helps the body rest, digest and recover.

Cortisol keeps the body on alert after the first rush. It is meant to drop once the threat is over.

When cortisol stays high for a long time, it can increase appetite and make the body store more fat.

Under stress, the thinking part of the brain loses some of its power, while faster, more automatic reactions take over. This is why it can be hard to think clearly in an exam or an argument.

Medical students in a month of heavy exam stress had more trouble switching their attention between tasks. Brain scans showed weaker teamwork in the networks that control attention.

The amygdala helps lock in memories of emotional events. This is why stressful moments can stay vivid for a long time.

Long exposure to stress hormones also affects brain areas involved in memory and thinking.

Stress can throw brain circuits for thinking, decisions, worry and mood out of balance. In the short term this can be useful. If it lasts, it can become a problem.

Long exposure to stress hormones affects brain structures involved in thinking and mental health. The effects depend on when in life the stress happens and how long it lasts.

With prolonged stress, the branches of brain cells in the prefrontal cortex can change shape.

Chronic stress can also cause brain changes that may contribute to anxiety, depression and addiction.

Chronic stress contributes to high blood pressure. Repeated surges of adrenaline can damage blood vessels and raise the risk of heart attack and stroke.

Stress signals from the brain affect the body’s hormones, nerves, immune system and metabolism.

How stress can affect you

• Changes in appetite, energy and interests
• Feelings of fear, anger, sadness, worry, numbness or frustration
• Headaches, body pains, stomach problems or skin rashes
• More use of alcohol or other substances
• Nightmares or problems sleeping
• Trouble concentrating and making decisions
• Worsening of chronic health problems and mental health conditions

When the stress response is used too often and never gets a chance to switch off, wear and tear builds up. Rest and support give the brain and body a chance to recover.

Strong, frequent, long-lasting hardship without supportive relationships can affect a child’s developing brain. Supportive relationships with caring adults help buffer a child’s stress response.

Teens and young adults often face stress from school, relationships and big life changes. Journaling, relaxation exercises, regular meals, sleep and reaching out to supportive friends and family can all help.

In 2025, most U.S. adults named division in society as a significant source of stress, and many said they felt isolated or needed more emotional support.

Research shows there are important differences between the sexes in how the brain responds to stress. Everyone deserves support, whatever their stress looks like.

Students under heavy exam stress showed changes in attention and brain activity. One month after the stress eased, they no longer differed from students who hadn’t been stressed.

In a small study, adults took an 8-week mindfulness course. The more their stress dropped, the more grey matter decreased in part of the amygdala, the brain’s threat detector.

Hard early experiences can have lasting effects on brain and body. The brain’s ability to change gives hope for approaches that use the brain–body connection to heal.

Exercise after a stressful event can relieve muscle tension and deepen breathing. Practices like yoga, tai chi and qi gong combine movement, breathing and focus.

In an 8-week study, city dwellers spent at least 10 minutes in a place that felt like nature, three times a week. Cortisol dropped more than usual, with the most benefit per minute at 20 to 30 minutes.

A review of slow-breathing studies found it affects heart rhythm and brain activity in ways linked to relaxation, along with feeling calmer.

A review of 29 studies with healthy adults found mindfulness-based stress reduction moderately helpful for stress, anxiety, low mood and quality of life.

Meditation is generally low-risk, but about 8% of people in studies had a negative experience, such as more anxiety. If you have a trauma history, talk with a therapist about what fits you.

In a brain-scan study, naming the emotion in an upsetting picture lowered activity in the amygdala and raised activity in a calming part of the prefrontal cortex.

People with close relationships with family and friends get emotional support that helps them handle chronic stress.

Staying connected with people you trust, and with community or faith groups, is one of CDC’s healthy ways to cope.

Getting enough sleep, with a regular bedtime and wake time, is a key way to care for your body under stress.

Hearing about negative events over and over can be upsetting. Limiting news and social media is one way to care for your mind.

Practicing gratitude, cutting back on caffeine and drinking less alcohol can help too.

Stress can help you meet a deadline. Brief, manageable stress is part of healthy development. It’s stress that is strong, constant and unsupported that causes harm.

Stress changes hormones, heart rate, blood pressure, digestion and immune signals. The brain directs it all.

The prefrontal cortex is very sensitive to stress in everyone. Taking breaks and asking for help is smart, not weak.

In one study, brain changes from a month of stress were gone a month after the stress eased.

Some people feel more anxious during relaxation or meditation, especially with a history of trauma. It’s OK to try something else, or to get guidance from a therapist.