Your body keeps its core temperature steady by moving blood toward or away from the skin, because blood flowing near the surface lets heat escape, while less blood near the surface holds heat inside.

When stress hits, the alarm system tightens the small blood vessels in the skin as part of getting ready to act, and it happens automatically, without you choosing it or even noticing it.

The fingers and face cool first. In lab tests the fingertips cooled while the skin over the chest stayed the same, which is why the chill often starts at the edges.

Your skin is packed with temperature sensors, and when they report a quick drop, the brain interprets it as cold, even when the room and your core temperature have barely changed at all.

The same alarm can raise goosebumps, because tiny muscles at the base of each hair tighten, a leftover from the days when fur helped animals hold heat or look bigger to a threat.

Some people get a hot flush first. Stress can warm you from the inside, then sweat and cooled skin swing you back to cold, so hot and cold can trade places.

None of this means you are getting sick. Stress moves core temperature only slightly and it stays within the normal range, so a real fever on a thermometer points to something else entirely.

The loop to break is the alarm itself. Once it settles, blood returns to the skin and the chill fades, often within minutes of the pressure easing.

Your skin does two jobs with heat: it releases heat when you are warm and holds it in when you are cool. The main control is how much blood is flowing through the tiny vessels just under the surface.

The hands, feet, nose and ears can open those vessels wide or shut them almost completely. That makes them the body’s fastest heat valves, and the first places to feel cold when the valves close.

This system is designed for weather and exercise. Stress asks it to do something different, sending blood toward the large muscles in case you need to act, so the skin gives up warmth to keep the core and muscles ready.

Doctors use the word chills for feeling cold, sometimes with shivering and pale skin. Goosebumps are related but separate, and a strong emotion like shock or fear can raise them on its own.

The fast route is the nervous system, where a stress signal travels down nerves to the small skin vessels and instructs them to tighten. In lab tests the vessels narrowed almost at once, and the fingertip cooled about 15 seconds later.

The slower route runs through stress hormones in the blood. They keep the alarm going for minutes rather than seconds, which is why a chill can linger after the moment that set it off has passed.

A purely mental task is enough. In two lab studies of 46 young adults, giving a speech and doing math out loud cooled the fingertips and finger base, while the skin under the collarbone did not change.

In a smaller study of 15 people, the fingers and nose tip cooled while people were only waiting for the same speech task. Nothing cold had touched them, so the anticipation of what was coming did it on its own, without any physical trigger.

People often say they were not that stressed, so it cannot be stress. The skin does not wait for a dramatic, obvious threat before it responds. In laboratory work, a narrowing that lasted only five seconds was enough to show up as a drop at the fingertip.

Waiting is a dose too. In the 15-person study, finger temperature fell while people were waiting, before the stress task had even started, and it stayed down through the task itself.

In animal research, stronger stressors cause longer-lasting temperature changes. That has not been mapped cleanly in people, so treat it as a likely pattern rather than a measured rule for humans.

Heat and cold can also happen at once. In a tiny study of five women, simply expecting a math test warmed the skin over heat-producing fat near the collarbone, a mixture that helps explain the hot-then-cold swing many people describe.

The classic moments have an audience: a talk, an interview, a hard conversation, bad news on the phone. Social pressure is exactly what the lab speech test copies, and it reliably cools the skin.

Then come the amplifiers, which have nothing to do with stress. After one night without sleep, six women in a laboratory lost heat faster, and a separate study of eight adults found that skin temperature control fell out of step. Late screens that cut sleep count here.

Hormones matter as well. Around menopause, many women experience cold chills after a hot flash, and some notice more cold spells than hot ones. Anemia, very low body weight and an underactive thyroid can also leave you feeling cold.

Medication changes belong on the list too, since stopping some antidepressants suddenly can bring flu-like feelings for a while. If several of these land in the same week as a big stressor, the chill has more than one cause.

Chills can feed themselves. Feeling cold out of nowhere is unsettling, so people monitor their bodies for the next one, and that constant monitoring keeps the alarm half switched on. Over time the body can start to fire the chill at smaller cues.

The encouraging news is how quickly the skin recovers. In the 15-person study, finger and nose temperatures climbed back up during the recovery period after the task, which shows the chill is a temporary state, not damage.

Breathing is the easiest lever. In a month-long trial of 108 adults, five minutes a day of slow breathing with a long exhale improved mood and slowed breathing more than the same time spent meditating.

When chills come with panic attacks, talking therapy has the best track record. A large review found that cognitive behavioural therapy was the most studied option and often did better than others, though the gains were modest.

One popular idea deserves retiring: that stress has worn out your adrenal glands, leaving you cold and drained. A review of 58 studies found no proof that this condition exists, and no hormone society recognises it.

The research also disagrees about the core. A major review says stress nudges core temperature slightly up in people. Yet a controlled lab study found gut temperature went slightly down, and a reading at the temple did not move.

The authors of that study said the animal version of stress fever does not carry over directly to humans. What stays the same is the skin: the fingers cool under pressure, and that is the part you feel.

The numbers are also small. The best lab studies tested 15 to 46 healthy young adults, and nobody has counted how often stress causes chills in the public. Hold the details loosely and the overall pattern firmly, because the direction of the skin changes is consistent across studies.