With temperatures in the UK breaking records on Tuesday, what is the impact of heatwaves on mental health?

Are heatwaves a concern for mental health?

“In recent years there’s been an increasingly large body of research showing us that heatwaves worsen outcomes for those with underlying psychiatric illnesses,” says Dr Laurence Wainwright, a departmental lecturer at the Smith school and the precision psychiatry lab at the University of Oxford.

“Rates of suicides go up, levels of mortality go up, for those with existing conditions symptoms can be worsened,” he adds, noting that for people with conditions such as bipolar disorder, extreme heat can trigger manic phases.

Prof Tahseen Jafry, the director of the Mary Robinson Centre for Climate Justice at Glasgow Caledonian University, says: “With increased temperature rises, there is evidence to show that there [are] more frequent visits to hospitals for mental health, mental illnesses and behavioural and mood disorders.”

One study from the UK, published in 2007, found a 3.8% increase in suicide rates for every 1C rise in average temperature above 18C.

Researchers have also found that higher temperatures are associated with an increase in aggression and violence – possibly due to the impact on various hormones – and can affect cognitive function, leaving people feeling fuzzy-headed..

Why does the heat affect mental health?

It is likely there are several factors at play. Among them, Wainwright notes, is that many people have interrupted sleep during heatwaves. “What the evidence shows us very, very clearly is that poor-quality sleep and/or shorter sleep duration can worsen outcomes in those, say, with major depressive disorder,” he says. “A couple of nights of broken sleep can be a trigger for the onset of their depressive phase.”

He adds that the heat can worsen some side-effects of psychiatric medication or in some cases make the medication less effective. What’s more, some medications affect the body’s ability to thermoregulate or otherwise impair individuals’ ability to take appropriate measures.

“The antipsychotics which we use in schizophrenia and bipolar, they can actually have an impact on people’s perception of thirst,” says Wainwright. “The body has a very good way of telling us when we’re thirsty, [but] when we’re taking these medications, that can be impacted – and during a heatwave that obviously poses problems for heat-related illnesses.”

People may experience indirect effects such as raised concerns over issues such as food insecurity or migration. Jafry says: “Those things can then affect people’s mental health and wellbeing because it’s about how do we cope with, and adapt to, these changing circumstances.”

Eco-anxiety can also take a toll, she says, noting that many young people experience stress regarding climate change. “[The term is] used to describe an anxious state about what’s happening immediately, but also about our future and how we’re going to deal with that,” Jafry says. “And I think that’s something that we are likely to see more of.”

What can we do?

As well as taking steps to keep cool and hydrated, Wainwright advises keeping medications out of the sun and remembering to take them, avoiding alcohol, taking steps to sleep well, and practising self-compassion, such as not criticising oneself for being less productive than usual.

He also recommends that people with mental health conditions speak to medical professionals if they notice a worsening in their symptoms, or issues related to their medication.

Wainwright adds that among other steps, health policy must be reoriented as understanding of the relationship between heat and mental health improves, and public education is needed around this relationship.

Jafry calls for dedicated mental health support, for example through trained community nurses, to help deal with the impact of heatwaves and other extreme events.

Wainwright says: “Heatwaves, and the effects they have on our mental health, are important reminders that the best thing we can do to help ourselves and future generations is to act on climate change.”