Why Does Hot Weather Make Me So Irritable, Anxious, and Unable to Sleep?
Feeling uncomfortable, irritable, or even angry when the weather turns hot is something almost everyone can relate to.
So, what’s really going on?
Most experts today believe that the exhaustion you feel in hot weather comes from the energy your body burns cooling itself down — sweating to release heat, which leaves less energy for everything else.
That sounds logical at first, but it doesn’t quite hold up. Does sweating really cost that much energy? Is perspiration alone enough to exhaust a person? If so, what about runners or athletes? Their bodies sweat constantly, non-stop, throughout intense exercise — yet they still have the energy to keep running and playing. Meanwhile, someone drained by the heat is doing nothing but sitting or lying down, breathless and exhausted, while sweat runs down their skin.
Most people — including experts — fall into the same mistake: assuming the body can spend its energy however it likes. But that’s not how it actually works.
Your body’s energy isn’t available on demand. It follows its own internal mechanism — and when the conditions aren’t met, that energy gets locked away. You can’t simply “decide” to access it.
Here’s what’s actually happening
The human body has to maintain a stable internal temperature of 37°C (98.6°F) for its organs to function properly. When the outside temperature rises, your body temperature rises with it — and since every internal process that produces energy also generates heat, this pushes your body temperature up even further. To keep from crossing that 37°C threshold, your body cuts back on energy production.
That’s what leaves you feeling tired and depleted. The hotter it gets, the more energy production gets cut — and the more exhausted you feel.
You can actually verify this mechanism through your own everyday experience: on cool days, you feel comfortable, work more efficiently (which is exactly why offices are kept air-conditioned — to keep employees productive), and eat more. On hot days, it’s the opposite: you feel drained, get less done, and often don’t feel like eating much at all.
Here’s why: in cool weather, your body “unlocks” more energy, letting you do more — and since you’re burning more, you need more food to refuel. In hot weather, your body restricts that energy, leaving you tired and less productive — and since less energy is going out, your appetite naturally drops too.
Why Hot Weather Triggers Feelings of Insecurity, Anxiety, and Sleeplessness
When your internal organs suddenly have less energy to work with, their function becomes compromised — and this shortfall registers in your body as a state of insecurity (feeling unsafe).
If you’ve read Demystifying Anxiety, Fear, and Anger, you’ll know the formula behind anger: Insecurity + a position of strength.
Hot weather already puts you in a state of insecurity. All it takes is one more perceived threat — where you feel you have the upper hand, the winning position, or simply that the other person won’t push back — and anger is triggered. Irritability is just a milder form of that same anger.
For example, an offhand comment from a family member wouldn’t normally bother you. But on a scorching hot day, that same comment can suddenly make you raise your voice or snap.
Why Does Hot Weather Also Cause Anxiety?
The formula behind anxiety is: Insecurity + a position of weakness.
Hot weather already puts you in that same state of insecurity. All it takes is one more perceived threat — one where you feel you’re on the losing end — and anxiety kicks in. Risks at work or in a relationship, for instance, are far more likely to spiral into anxiety when the weather is oppressively hot.
Why Does Hot Weather Make It Harder to Sleep?
During 8 hours of sleep, you’re essentially defenseless — any threat could put your life at risk. So as a safeguard, your brain only allows you to fall asleep once it senses that you’re safe. Hot weather creates a sense of insecurity, making it harder to fall asleep in the first place. And even if you do manage to drift off, rising temperatures can still wake you up partway through the night.
In short, hot weather doesn’t directly cause irritability, anxiety, or sleeplessness. It does exactly one thing: it pushes your body into a state of insecurity by forcing it to cut back on energy production in order to keep your internal temperature stable. From that state of insecurity, depending on whether you perceive yourself as being in a position of strength or weakness in any given moment, it shows up as anger or as anxiety. And when your body can’t find enough safety to properly fall asleep, insomnia follows as an inevitable result.
Once you understand this mechanism, you can stop blaming yourself for “being so irritable lately” or “overthinking everything lately” every time the weather heats up — because it was never a change in your personality. It’s simply your body responding exactly the way it was built to, in order to survive.