Dear friends, clients, and community,
This June has been unlike any other. The Met Office has now issued a Red Warning for Extreme Heat — the highest alert level in Britain — describing conditions not seen since July 2022, but this time with a critical difference: relentless tropical nights where temperatures do not drop below 20°C. Records have been broken across the country. Somerset reached 36.7°C. Hospitals have declared critical incidents. The M25 saw people treated for heat illness after being trapped in traffic.
At London Trusted Therapy, we want to write to you today not about sun cream or ice lollies — though both have their place — but about something far less visible: what this extraordinary heat is doing to your mind, your nervous system, your closest relationships, and your sense of self.
Because the heat is not just a physical event. It is, as the science increasingly tells us, a psychological one.
To understand why you may feel unlike yourself this week, we need to start with the brain. When the body is exposed to sustained high temperatures, it triggers a cascade of neurobiological changes that affect every aspect of your emotional and cognitive functioning.
The first and most important is cortisol. As temperatures rise, the body releases increasing amounts of cortisol — the primary stress hormone — which heightens feelings of agitation, anxiety, and mood instability. Simultaneously, the parasympathetic nervous system — the branch responsible for calmness, rest, and emotional regulation — becomes suppressed. The result is a physiological state that closely resembles anxiety: elevated heart rate, shallow breathing, hypervigilance, and an inability to settle. Your body is, in effect, in a sustained state of low-grade threat response — not because something is wrong with you, but because your nervous system is responding precisely as it is designed to.
What this means in practice is that you may find yourself reacting rather than responding. Small things feel large. Old irritations re-emerge. Patience thins. This is not a character flaw. It is neurochemistry.
The picture is compounded by the effect of heat on neurotransmitter systems. High temperatures disrupt serotonin regulation — the system underpinning mood stability, optimism, and impulse control — and affect dopaminergic pathways involved in motivation, pleasure, and reward. In short, the brain’s capacity to generate wellbeing is metabolically compromised before we have even got out of bed.
Of all the mechanisms through which this heatwave is affecting mental health, disrupted sleep is perhaps the most significant — and the most underestimated.
Sleep is not a passive state. It is the time during which the brain processes emotional experiences, consolidates memory, and restores regulatory capacity. High temperatures specifically reduce time spent in slow-wave and REM sleep — the phases most crucial for emotional processing and psychological restoration. A UK national survey found that 52% of people struggle to sleep during hot weather. In a heatwave of this magnitude, with tropical nights preventing recovery between days, that figure is almost certainly higher.
The clinical consequences are significant. Sleep deprivation is strongly linked to elevated anxiety, increased irritability, impaired emotional regulation, and reduced cognitive performance. For those already living with depression, poor sleep worsens concentration, hopelessness, and anergia. For those with bipolar disorder, even a few nights of reduced sleep can be a classic trigger for mood switching. For anxiety disorders, sleep loss raises physiological arousal and increases sensitivity to bodily sensations — creating a feedback loop where anxiety impairs sleep, and sleep loss amplifies anxiety.
If you have been feeling emotionally raw, cognitively foggy, or strangely tearful this week — sleep debt may be playing a larger role than you realise.
One of the most striking and underreported effects of extreme heat is what it does to our relationships. The research here is both sobering and, in a strange way, liberating — because it tells us that the arguments and tensions that have erupted in households across the country this week are not just personal failures. They are, in part, meteorological.
Social psychologist Craig Anderson demonstrated in a landmark series of studies that people in uncomfortably warm rooms consistently rated neutral interactions as more hostile than those in cooler environments. The heat did not create conflict — but it primed people to perceive and interpret conflict where none existed. We become, in the heat, more likely to read aggression into an ambiguous tone, more likely to respond to a neutral comment as a provocation.
Research published in the Sage journal Social Psychological and Personality Science found a clear association between extreme heat days and increases in domestic abuse. A global scoping review noted that each 1°C increase in annual temperature is associated with an average 6% rise in homicide rates. Intimate partner violence increases during heatwaves, with effects particularly concentrated in enclosed spaces — homes, flats, households where people are trapped together in the heat with no escape.
This is not to excuse harmful behaviour — never that. But it is to say that if your household has been more volatile this week, if you and your partner have found yourselves in the same circular argument for the third time, if you have snapped at your children and felt immediate guilt — you are not uniquely broken. You are human, in a heat event, sleep-deprived, and cortisol-saturated.
What Helps in Relationships Right Now
- Name the dynamic explicitly: ‘I think we’re both heat-depleted and sleep-deprived. Can we pause this until tomorrow morning?’
- Reduce the physical temperature of the space before attempting difficult conversations — even briefly moving to a cooler room changes the neurological context.
- Lower your mutual expectations this week. This is not the time for important decisions, challenging talks, or resolving longstanding grievances.
- Physical touch — a hand, a cool damp flannel — can activate the parasympathetic nervous system and interrupt an escalation cycle.
- If you are in a relationship that is already under strain, please reach out to us. The heat will pass; the underlying patterns will remain.
For those living with ADHD — whether diagnosed, self-identified, or suspected — this heatwave presents a specific and intensified challenge. To understand why, we need to understand something fundamental about the ADHD brain.
ADHD is, at its neurobiological core, a condition of dysregulated dopamine and norepinephrine systems — the very neurotransmitters that govern emotional regulation, impulse control, attention, and the capacity to delay reactions. The prefrontal cortex (PFC) — responsible for top-down emotional regulation — is already operating with reduced efficiency in ADHD. What heat does is further compromise exactly those systems that are already the brain’s weak link.
Research published by the Karolinska Institute describes ADHD as involving a gradient between ‘cool’ executive functions (attention, planning, working memory) and ‘hot’ regulatory circuits (emotional reactivity, impulse control, reward sensitivity). Heat stress loads the hot circuits whilst draining the cool ones. The result for many ADHD individuals is a dramatic increase in what clinicians call emotional dysregulation: intense, fast-moving emotional responses that feel overwhelming from the inside and alarming from the outside.
A peer-reviewed study published in 2025 examined over 4,400 emergency department visits for depression and suicidal ideation in children and young people with ADHD. It found that heatwave exposure was associated with significantly increased risk of acute psychiatric crisis in this population, with effects present same-day, lagged, and cumulative across multi-day heat events. The authors described ADHD traits — impulsivity, emotional reactivity, and sensory sensitivity — as ‘established markers of environmental susceptibility’.
For adults with ADHD, the picture is equally complex. Stimulant medications (methylphenidate, amphetamine salts) increase cardiovascular load and metabolic rate in heat — producing sensations that can closely resemble panic and anxiety. Many ADHD adults will find their medication feels ‘different’ this week: less effective, or producing unexpected side effects. This is a physiological reality, not a sign of deterioration.
Practically, ADHD individuals may find this week brings: more frequent emotional outbursts; increased impulsivity; a collapse of executive function (tasks feel impossible); hypersensitivity to frustration; and a sense of being ‘out of control’ that can provoke shame. Please hold this gently. This is neurochemistry meeting meteorology, not a measure of your character or capability.
Supporting ADHD During the Heatwave
- Prioritise cooling above all other interventions — the brain literally cannot regulate when overheated. A cool shower, air conditioning, or even a cool flannel to the wrists and neck is not a luxury; it is clinical.
- Reduce demands and expectations ruthlessly. Postpone cognitively demanding tasks. This is not giving up; it is adaptive.
- If you take stimulant medication, stay extremely well hydrated and monitor how you feel. Speak to your prescriber if you are concerned.
- Use externalised structure more heavily than usual: written lists, timers, visible reminders. Internal self-regulation is under extra load.
- Communicate with those around you: ‘I am struggling more than usual this week because of the heat.’ Naming it reduces shame and pre-empts misunderstanding.
For autistic individuals, extreme heat creates what might best be described as a sensory perfect storm. To understand this, we need to appreciate that autism involves not just differences in social communication, but profound differences in the way the sensory nervous system processes the environment.
Autistic individuals frequently experience interoceptive differences — altered awareness of what is happening inside the body, including temperature. Research published in Scientific Reports found that autistic individuals show increased intra-individual variability in thermal perception: the brain’s registration of temperature is less reliable and more erratic. This creates a specific risk: an autistic person may not register that they are dangerously overheating until they are already in crisis — at which point the signal arrives not gradually but abruptly, contributing to what is experienced as a sudden meltdown or shutdown.
This is compounded by autonomic nervous system differences common in autism: higher resting heart rate, lower heart rate variability, and erratic sympathetic nervous system responses. In heat, these differences create a neurological environment that is already closer to the edge. When sensory input from heat, humidity, sweat, and tight clothing is added to an already dysregulated autonomic baseline, the threshold for overwhelm is drastically reduced.
Sweating itself — both the sensation and the social dimension of it — can be profoundly dysregulating for autistic individuals with tactile hypersensitivity. Humidity creates a pervasive, unescapable sensory environment that cannot be modulated or controlled, unlike other sensory inputs that can sometimes be reduced by removing a tag from a collar or leaving a loud room. The heat simply is, everywhere, inescapably.
Autistic burnout — the profound exhaustion that accumulates from sustained sensory and social demand — is significantly more likely during heatwaves. For late-diagnosed autistic adults in particular, who may have spent decades without the language to describe their sensory experience, this week may feel overwhelming in ways that are hard to articulate. You are not being dramatic. The science supports your experience.
Supporting Autistic Individuals During the Heatwave
- Proactively build in sensory retreats: cool, quiet, low-stimulation spaces, even briefly, throughout the day.
- Prioritise familiar, comfortable, loose-fitting clothing even if it does not ‘look’ appropriate for the occasion.
- Reduce social and sensory demands wherever possible. Cancelled plans are not failure; they are self-preservation.
- For parents and carers: increased meltdowns and shutdowns this week are neurologically driven. They require compassionate co-regulation, not correction.
- Hydration is especially important for autistic individuals who may not reliably notice thirst signals. Build in scheduled drinking rather than waiting for thirst.
- Consider whether interoceptive support — body scans, gentle somatic exercises — might help build awareness before the warning signals become crisis signals.
If you are currently taking psychiatric medication of any kind, it is important to be aware that heat changes the way many medications work in the body. Older antidepressants such as tricyclics can increase vulnerability to cardiovascular stress under heat conditions. SSRIs may cause sweating patterns that interfere with thermoregulation and sleep. Antipsychotics — including risperidone and aripiprazole — block dopamine receptors in thermosensitive pathways and can impair the body’s ability to vasodilate, effectively trapping heat. Stimulants for ADHD increase heart rate and metabolic demand.
None of this means you should alter your medication without consultation. But it does mean: tell your prescriber if you are feeling unusually unwell. Stay extremely well hydrated. Do not assume that strange physical sensations are purely psychological.
For your nervous system:
- Cool your body physically before attempting emotional regulation — a cool damp cloth to the back of the neck activates the vagal brake and can interrupt a stress spiral within minutes.
- Practice the physiological sigh: a double inhale through the nose, followed by a long exhale through the mouth. This is the fastest known way to down-regulate the autonomic nervous system.
- Name your state — ‘I am dysregulated because I am overheated and sleep-deprived’ — with compassion rather than judgement. Self-labelling activates the prefrontal cortex and reduces limbic reactivity.
For sleep:
- Sleep in the coolest room in your home. Block direct sunlight during the day with closed curtains.
- A cool (not cold) shower before bed lowers core body temperature, which is the primary signal for sleep onset.
- Avoid alcohol in the evenings: it fragments sleep architecture, prevents REM sleep, and worsens anxiety and mood the following day.
For your relationships:
- The sentence ‘I’m not at my best right now because of the heat — can we revisit this tomorrow?’ is one of the most powerful tools in your relational toolkit this week.
- Check in with vulnerable people in your network: those who live alone, who have mental health conditions, who are elderly. A phone call can be lifesaving.
For those with ADHD and autism:
- This week requires explicit, deliberate reduction of demand. Build in more recovery time, more sensory breaks, and more explicit communication about your needs.
- If you support a neurodivergent child or partner, remember that heightened reactivity this week is neurologically driven. Regulation before connection. Connection before correction.
If this week has been hard — if the heat has amplified something that was already fragile, disrupted your sleep, strained your relationships, or made you feel unlike yourself — please do not minimise it or wait for it to pass without support.
The heat will break. But the patterns it has illuminated — in our nervous systems, our relationships, and our sense of self — are worth attending to.
That is exactly what we are here for.
With warmth — and a genuine wish for cooler nights ahead,
PhD | MA | BSc | PGDip | Adv.Dip (Level 7, COSRT) | BACP Accredited | FMBPsS
