When the heat gets in your head: Why climate change is also a mental health crisis

Australia is heading into one of its warmest winters on record, and many people are already feeling the change. Milder nights, warmer days, and fewer signs of the cool season we’ve come to expect.

But while we adjust to the weather, something else is quietly shifting too: our mental wellbeing. As temperatures rise even outside of summer, researchers are seeing a clear link between extreme heat and mental health challenges.

For people already living with anxiety, depression or other mental health conditions, hotter days can make symptoms worse. And for many others, it adds a layer of stress and exhaustion that’s hard to name but hard to ignore.

A new study published in Nature Climate Change has confirmed what health professionals, researchers and many lived experiences have long suggested—that climate change is no longer just a threat to ecosystems or physical health. It’s also fuelling a mental health crisis, particularly for those already living with mental and behavioural disorders (MBDs).

The heat is getting into our heads, literally and figuratively, and the consequences are unfolding faster than most of us realise.

The study, one of the most comprehensive of its kind, analysed the burden of high temperatures on mental health in Australia from 2003 to 2018. It found that exposure to high temperatures significantly worsens outcomes for people living with MBDs including depression, anxiety, bipolar disorder, schizophrenia and substance use disorders.

Let’s look at the numbers.

The findings have already attracted international attention, with coverage in global outlets and other publications underscoring the urgent need to connect climate science with mental health policy.

It’s long been understood that heatwaves strain emergency departments and increase physical health risks. But the mental health effects of rising temperatures are only recently gaining public attention despite being just as consequential.

Heat disrupts sleep, which undermines emotional regulation and cognitive clarity. It increases physiological stress and agitation, making irritability and aggression more likely. For people taking psychiatric medication particularly antipsychotics, mood stabilisers or substances that affect thermoregulation, high temperatures can interfere with how the body processes those drugs, raising the risk of heatstroke and dehydration. And when it’s too hot to leave the house, social isolation deepens, especially for people already at risk of loneliness or disconnection.

These impacts are not theoretical. Clinicians across Australia report more admissions during heatwaves, particularly among patients with complex mental health needs. Outdoor workers, people without stable housing, and those living in poorly ventilated or overcrowded homes face compounded risks (mental, physical and environmental) all at once.

Even slight increases in night-time temperatures can affect sleep quality, which in turn reduces emotional resilience and sharpens feelings of anxiety or low mood the next day.

Emerging research suggests that prolonged exposure to high heat may increase inflammation in the brain, an effect linked to mood disorders such as depression and anxiety.

Many psychiatric medications impair the body’s ability to regulate heat or retain fluids, increasing vulnerability to heat-related illness or adverse drug reactions.

When it’s too hot to go outside, opportunities for connection, physical activity and structure diminish which can lead social isolation and emotional distress.

Some studies have found a direct correlation between extreme heat and suicide rates, particularly during prolonged heatwaves with limited cooling options.

The mental health impacts of heat aren’t evenly distributed. Those already living with mental illness often experience intensified symptoms during extreme weather events. People with fewer financial resources may struggle to afford cooling or may live in housing not designed to withstand prolonged heat.

Older adults, remote Aboriginal and Torres Strait Islander communities, renters, and people in aged care are particularly vulnerable due to the intersection of environmental exposure and reduced access to adaptive infrastructure.

The reality is this: climate vulnerability often overlaps with social and health inequity. And yet, our national systems are only just beginning to acknowledge that mental health must be part of the climate adaptation conversation.

That said, the seeds of progress are being sown. Advocacy groups like the Climate and Health Alliance and organisations like Mental Health Australia are beginning to build bridges between health and environmental planning. But systemic change takes time and time is what climate models suggest we’re running short on.

We often measure climate change in melting glaciers, rising sea levels, and burnt bushland. But we must also measure it in the stories we don’t always see. Burnout, anxiety, disrupted sleep that that builds over long, hot days with no reprieve.

Climate change is not only reshaping our environment, it’s reshaping how we feel, how we cope and how we connect.

The next step is to design services, systems and spaces that reflect it.

Some areas where positive change can begin:

These are just some of the actionable steps towards a more resilient and responsive system. Because the truth is, mental wellbeing can’t wait for ideal conditions. It needs to be supported now, in real time, with care that adapts as the world around us does.

When the pressure builds due to heat, stress, uncertainty or ongoing mental health concerns, Leora Healthcare is here to help. Through our mental health platform, we offer practical, person-centred support that meets people where they are.

Experience support that goes deeper. Contact Leora today to get started.