Numerous individuals view stress as inherently negative, yet it's not so straightforward. Stress is a natural and highly beneficial bodily reaction when we perceive a situation as threatening, explains Dr. Ralf Suhr, chairperson of the Berlin-based Health Literacy Foundation, dedicated to empowering informed health choices.

Chemical messengers called stress hormones, for example, noradrenaline, adrenaline and cortisol, are released into the bloodstream. Energy stores are mobilized, and we become more alert and able to react faster. This "fight-flight-or-freeze" mode was vital for our prehistoric ancestors when, say, they suddenly faced a dangerous animal.

Nowadays, however, it's rarely an encounter with a wild bear or the like that triggers a stress response. Rather, it's everyday stressors such as a demanding boss, familial or financial problems, constant time pressure or sensory overload in our fast-paced, digitally interconnected world.

This can cause chronic stress, leaving the body little opportunity to return to a normal, relaxed state, and thereby encouraging biochemical processes that can lead to illness.

"Studies haven't definitively shown a direct connection between stress and certain diseases, however," says Suhr. Nevertheless, various diseases are linked to chronic stress, which can suppress the immune system and make you more susceptible to infections. In addition, stressed people often develop unhealthy behaviors, for example sleeping too little, smoking or eating hastily or unhealthily.

Here's how stress impacts specific body areas:

Stress can result in indigestion, even of foods you normally tolerate well, and "this makes many people prone to diarrhea," says psychiatrist and stress researcher Dr. Mazda Adli, chief physician at Berlin's Fliedner Clinic and head of the affective disorders research division at Charité University Hospital. Chronic stress can also make your bowels sluggish, reduce your appetite, cause heartburn and lead to irritable bowel syndrome, according to Adli.

Acute stress increases heart rate and blood pressure. Chronic stress can lead to medical conditions such as chronic high blood pressure. "Cardiac arrhythmias (irregular heartbeat) are possible as well," Adli says. Chronic stress is also a risk factor for heart attacks and strokes, a risk that's exacerbated by unhealthy behaviors such as smoking.

Stress can result in muscle tension. The muscles in your neck may get so tight that you can hardly turn your head. Back pain can occur too. This all could lead to uneven weight distribution in your musculoskeletal system, with possibly painful consequences such as a herniated intervertebral disc or lumbago.

Stress is thought to be a possible contributor to metabolic disorders such as Type 2 diabetes and high cholesterol levels. "Because it feels threatened, a body under stress mobilizes more energy stores, both sugar and fat," explains Adli.

"At the same time, stress hormones promote insulin resistance," increasing blood sugar levels. What's more, the stress hormone cortisol causes the body to constantly replenish its sugar and fat stores, which can result in the body making more energy available than it ends up needing. The extra sugar and fat can contribute to a buildup of harmful belly fat, constrict blood flow, strain blood vessels and encourage metabolic disorders.

"The brain, and by extension the psyche, react very sensitively to chronic stress," says Adli. The constant state of alert leads to mental illnesses: "The best-known psychological complication of stress is depression," Adli says.

The increased release of cortisol into the bloodstream can also have adverse effects on concentration, and constant stress can cause memory problems. Since stress is usually accompanied by anxiety, it can precipitate anxiety and panic attacks over the medium and long term.

So if you realize you're chronically stressed, you should try to do something about it. A good way to start is by making sure to take regular recuperative breaks during your day. They could involve brief mindfulness exercises such as focusing on your breathing. Regular exercise helps too. For lasting relief from stress, it's important to change stress-promoting thought and behavior patterns, perfectionism being one. Cultivating friendships and pursuing a hobby are beneficial as well.

"All of these things are not only conducive to mental relaxation and positive emotions but also directly counteract your body's constant state of biological alert," Adli says.