There are days when nothing particularly goes wrong and yet, everything feels tougher. You’re more irritable than usual. Your patience runs thinner. Small inconveniences feel disproportionately frustrating. You feel tired, but not in a way that rest seems to fix. It’s easy to attribute this to stress, personality, or “just having a bad day.” But sometimes, the explanation is far more physiological. Sometimes, it’s the heat…

When Temperature Becomes a Psychological Factor

We often think of mood as something shaped by thoughts, experiences and circumstances. But the body plays a far more active role than we give it credit for. In high temperatures, the body is constantly working to maintain internal balance. This process called thermoregulation, requires energy. Blood flow shifts, hydration levels fluctuate, and the nervous system remains more activated than usual. This subtle, ongoing strain does not stay confined to the body. It spills over into the mind.

The Hormonal Link

Heat doesn’t just make you uncomfortable it influences the very systems that regulate mood.

Cortisol (the stress hormone): Prolonged heat can increase baseline stress levels in the body. Even without external stressors, the body behaves as though it is under strain. The result? You feel more on edge, more reactive, and less able to tolerate frustration.

Serotonin (mood regulation): While sunlight is often linked to improved mood, excessive heat can disrupt sleep and physical comfort both of which are essential for stable serotonin functioning. Low-quality sleep, especially, has a direct impact on mood regulation.

Melatonin (sleep-wake cycle): Hot nights interfere with the body’s ability to cool down – an essential step for initiating sleep. When sleep is disrupted, emotional regulation is often the first thing to suffer.

Why You Feel More Irritable

Irritability in the heat is not simply a personality flaw or a lack of patience. It is, in many ways, a reduced capacity. When the body is already working harder to cope with environmental stress, there is less bandwidth available for emotional regulation. This means you react faster, you tolerate less and you also recover more slowly from minor stressors. What would normally feel manageable begins to feel overwhelming.

Heat also affects how we think. Research suggests that high temperatures can impair attention, slow down cognitive processing, and reduce decision-making efficiency. In everyday terms, this can feel like: Brain fog; Difficulty concentrating; Increased mental fatigue; and a sense of being ‘slower’ or less sharp. This cognitive strain adds another layer of frustration, mainly for individuals used to functioning at a high level.

Summer is often associated with ease of holidays, lightness and relaxation. But for many, the internal experience doesn’t match this expectation. Instead of feeling energised, they feel drained. Instead of relaxed, they feel restless. This mismatch can create an additional layer of self-judgment: “Why am I feeling this way when I’m supposed to be enjoying this?” But the expectation itself is flawed. Because heat, in excess, is not inherently relaxing. It is demanding.

A More Compassionate Understanding

Recognising the link between heat, hormones and mood allows for a shift from self-criticism to self-awareness. Instead of assuming: “I’m being unreasonable,” it may be more accurate to consider: “My system is under strain.” And when the system is strained, the goal is not to push harder but to support it. Small adjustments can make a meaningful difference:

• Prioritising sleep hygiene in warm conditions
• Staying adequately hydrated even mild dehydration affects mood
• Reducing cognitive load during peak heat hours
• Allowing for shorter patience thresholds without self-judgment
• Creating physical cooling moments which often lead to mental relief

Remember, these are not indulgences. They are regulation strategies. We often treat mood as something that should be managed purely through mindset. But the mind does not operate in isolation. It is deeply influenced by the body and the body, in turn, is influenced by the environment. Sometimes, what feels like irritability is physiology. What feels like low mood is fatigue. What feels like emotional overwhelm is simply a system pushed beyond its comfort zone. And understanding that does not reduce the experience, it makes it easier to respond to it, with a little more clarity and a little less self-blame!

[Psychologist Mehezabin Dordi practices at Sir H N Reliance Foundation Hospital, provides effective therapeutic interventions for psychological and psychiatric concerns. Having counselled over 2,500 patients and caregivers, she also conducts trainings and webinars. Connect: dordi.mehezabin@gmail.com]