Recently, my husband and I embarked on what should have been a pleasant spring errand: a stroll to the local farmer’s market. But a passing heatwave had made it unseasonably hot outside. I cut him off on the sidewalk and he snapped at me, so I snapped at him for snapping at me. We spent the rest of the excursion in sweaty, stony silence. When we were almost home, he said, miserably: “I’m sorry! It’s just so hot.”Our grouchiness was not simply a weakness of spirit. “Heat doesn’t just affect your body,” said Dr Susan Albers, clinical psychologist at the Cleveland Clinic. “It affects your mood too.”Studies have shown that on hotter days, rates of aggression tend to increase, as do incidents of road rage, violence and even emergency room visits for mental health concerns, Albers says.Why does excessive heat make us so cranky, and how can we better manage it? We asked experts.Graphic with three lines of text that say, in bold, ‘Well Actually’, then ‘Read more on living a good life in a complex world,’ then a pinkish-lavender pill-shaped button with white letters that say ‘More from this section’ How do hot temperatures affect the body?“Hot temperatures have cascading effects on the body,” said Dr Craig Sawchuk, a psychologist at the Mayo Clinic in Rochester.When it gets hot, your body kicks into overdrive, working hard to regulate core body temperature so it stays in a safe range – generally between 97F and 99F (36.1C and 37.2C).One of the first things that happens is that your vascular system (the vessels that carry blood and lymph fluid, such as veins and arteries) expands to allow more blood to flow more quickly throughout the body, Sawchuk explains. This brings more blood closer to the surface of the skin, decreasing insulation and allowing heat from within the body to dissipate. (When it’s cold, the opposite happens: your vascular system contracts, and blood is further from the surface of the skin, which keeps more of your internal heat contained.)Your heart must pump more blood to cool the body, leading to an elevated heart rate.Expanding blood vessels also trigger your sweat response. And while sweat can help cool you down, Sawchuk warns that excessive sweatiness can make you vulnerable to dehydration, which can lead to muscle cramps, headaches, fatigue, trouble focusing and emotional changes.But not everyone experiences heat in the same way, notes Albers. Nor is there a universal consensus for what “hot” means. Generally, she says, when temperatures climb into the upper 80s and 90s (or the 30s in celsius), that is when heat puts extra stress on the body.Some people are much more sensitive because of the way their body regulates temperature, or how and where they were raised. By contrast, those who grew up in hot climates tend to be better acclimated and have greater heat tolerance.Older adults and younger children have a harder time regulating their internal temperatures, Albers says. Additionally, some medications, including antidepressants, stimulants, antihistamines and blood pressure medications, can make it harder for the body to cool itself down.“People with chronic health conditions, those who are pregnant, and anyone who works or exercises outdoors are also at a greater risk,” she says.Some personality traits, such as neuroticism, also appear to increase the likelihood of worse emotional responses to hot temperatures, said Dr Kim Meidenbauer, assistant professor of psychology at Washington State University.skip past newsletter promotionafter newsletter promotionWhy do hot temperatures make (some of) us cranky?“The discomfort is certainly a major part of it,” says Meidenbauer. It’s hard to be in a good mood when you feel like a hot, wet lump. This discomfort is inherently unpleasant, but can also affect our responses to stimuli, because the body’s response to heat – increased heart rate, sweating and shortness of breath – can feel similar to emotional distress.For example: if you feel your heart rate increasing and someone says something annoying, you might take your rising heart rate to be a sign of irritation or anger rather than a way your body is coping with uncomfortable heat. “If your body wasn’t working hard and your heart rate was lower in that same situation, you might just roll your eyes and brush it off as someone being rude, and you wouldn’t have this same experience of feeling irritable,” she says.Heat can also lead to worse sleep, which can further erode our ability to tolerate stress and irritation, says Sawchuk.How do we better manage hot temperatures?“Being proactive and aware is key,” says Meidenbauer. Be aware of how you respond to heat, and keep track of weather conditions.Other tips include: