A short walk to the farmers market can turn into a tense, silent standoff once the temperature spikes. Snapping at a spouse over nothing, feeling irritated by every small inconvenience or losing patience faster than usual are common experiences once a heat wave rolls in, and experts say that reaction is not just a character flaw.
Heat affects more than the body, Research has shown that on hotter days, aggression tends to rise, along with incidents of road rage, violence and even emergency room visits for mental health concerns, Albers says.
How heat affects the body
Hot temperatures set off a chain reaction throughout the body, as the body works to keep its core temperature within a safe range, generally between 97 and 99 degrees Fahrenheit, several systems kick into overdrive at once.
- The vascular system expands, allowing more blood to flow closer to the skin’s surface so heat can escape more easily. In cold weather, the opposite happens, and blood vessels contract to trap warmth inside the body.
- The heart pumps faster to help cool the body, leading to a noticeably elevated heart rate.
- Expanding blood vessels also trigger sweating, which helps regulate temperature but can lead to dehydration if it becomes excessive. Dehydration in turn can cause muscle cramps, headaches, fatigue, difficulty concentrating and shifts in mood.
Not everyone experiences heat the same way, and there is no single agreed upon definition of what counts as hot. Generally speaking, once temperatures climb into the upper 80s and 90s, the body starts to feel real added stress.
Some people are simply more sensitive to heat depending on how their bodies regulate temperature or where they grew up, while people raised in hot climates tend to be better acclimated. Older adults and young children also struggle more to regulate their internal temperature, according to Albers, and certain medications, including antidepressants, stimulants, antihistamines and blood pressure drugs, can make it harder for the body to cool down. People with chronic health conditions, those who are pregnant and anyone who works or exercises outdoors face a higher risk as well. Certain personality traits, including neuroticism, also appear linked to stronger negative emotional reactions to heat.
Why heat makes people irritable
Simple physical discomfort plays a major role. Feeling sweaty and overheated is inherently unpleasant, but it can also distort how people interpret their own physical reactions. The body’s heat response, including a faster heartbeat, sweating and shortness of breath, can feel a lot like emotional distress.
A rising heart rate paired with something mildly annoying can easily get misread as anger or irritation, rather than the body simply working to cool itself down. In cooler conditions, that same mildly annoying moment might barely register. Heat can also disrupt sleep, which further chips away at a person’s ability to handle stress and frustration.
4 ways to manage the heat
Staying proactive and paying attention to personal reactions is key. Tracking weather conditions and noticing early signs of overheating can help prevent a bad mood from spiraling.
- Avoid the hottest stretch of the day, generally between 10 a.m. and 6 p.m., and schedule errands or outdoor activities for the cooler morning hours instead.
- Reset an overstimulated nervous system by stepping into air conditioning, sitting in a dark room or splashing cool water on the face. Public spaces such as malls, libraries, movie theaters and community cooling centers can help when air conditioning isn’t available at home.
- Keep a cooling kit on hand with a reusable water bottle, portable fan, cooling towel, sunscreen and electrolyte packets.
- Check in on children, older adults and others who are more vulnerable to heat, watching for dizziness, headaches, irritability or confusion, and get them to a cool space quickly if those symptoms appear. Checking on neighbors, older relatives and people who live alone during heat waves can also make a real difference.
Ultimately, there is only so much anyone can control when the temperature climbs. Some discomfort during a heat wave is simply unavoidable, but understanding why the body and mood react the way they do can make it easier to stay calm when the mercury rises.
