Stolen Sleep and Shrinking Brains – The Impact of Climate Change on Rest
Written by Hauwa Busari
Imagine this: A child grows up in a city where nights no longer bring relief. Their room is stifling. The fan hums, but the heat clings to their skin. They toss and turn, waking up, night after night. Fast forward 60 years. That same child, now much older, begins to forget not just where they last left their keys, but who their daughter or son is.
This may seem a stretched connection, but studies continue to highlight the long-term links between sleep and brain performance, providing the basis for why we must be called to action.
A new study, recently featured in Science News and the Journal of Clinical Sleep Medicine, found something both powerful and chilling: spending less time in deep and REM sleep is linked to brain shrinkage in regions vulnerable to Alzheimer’s disease. These stages don’t just rest the body; they protect the brain.
As a researcher studying the impact of room temperature on sleep architecture, this study hit home. If sleep is the brain’s nightly detox cycle, then temperature is the switch that turns it on or off. Many people do not actively think about this, and so the urgency remains unrealised. Ultimately, room temperature at night doesn’t just affect comfort; it shapes memory, mood, and long-term brain health. And now, climate change is quietly worsening these outcomes.
In my analysis of climate data from Lagos state, Nigeria, over the past 20 years, I found that the coldest periods of the year are becoming increasingly rare. What used to be cool, rainy nights are now warmer, shorter, and more restless. This isn’t speculation, it’s a documented trend that shows our window for restorative sleep steadily shrinking.
Hourly temperature comparison for Lagos in 2005 vs 2025, Credit: Author
Moving forward, we begin to see what the future holds, and it’s likely to include more sleepless nights.
Now let’s talk about the UTCI: the Universal Thermal Climate Index. It’s a comprehensive measure that doesn’t just consider air temperature, but also takes into account wind speed, humidity, solar radiation, and how these factors impact the human body’s thermal comfort.
Below, you will find the weekly average UTCI projections, based on climate data analysis:
🟧 2025: 32.6°C 🔴 2050: 35.1°C 🟢 2080: 36.3°C
Weekly Average UTCI Trends in Lagos, Nigeria (2025–2080). Credit: Author
At first glance, some people may say, “Well, it’s just 32 degrees, how bad could that be?”. Yet when you consider the context of what these temperatures mean for the human body at different points during life, these predicted rises become much more serious. These numbers are far from “just fine.” To understand their impact, we need to compare them to thresholds for thermal comfort and health risk levels across different population groups.
If you take a healthy adult, the ideal maximum temperature for their sleep and recovery is around 26°C, already much lower than the temperatures we will begin to see. Now take adults with cardiovascular conditions like diabetes, hypertension, heart disease, or a history of stroke, or take children, who are, as a population, naturally more vulnerable to heat stress. For these groups the safe limit drops to around 23°C, for former, and to between 16°C and 20°C for the latter.
Now think about UTCI again. We are heading toward averages well above 32°C, not peak heat, but averages. That means that there will be whole weeks where nighttime never truly cools down. Entire months where even the healthiest bodies are pushed to the edge, and where vulnerable groups face real risk. And this is not a future far away, it’s already beginning.
And here’s something else to think about: We spend 90% of our lives indoors. That’s basically our entire lives, unless you plan on sleeping under a mango tree! Which is why our homes, rooms, and buildings must become part of the climate solution because, as nighttime temperatures rise, deep sleep declines, and as deep sleep declines, cognitive functioning suffers. Before long, countless people will endure sweltering nights without relief, transforming sleep into a rare commodity and steadily eroding our health.
The data and the predicted consequences can be daunting, but they should also a clarion call to innovate.
Unless we act, climate change is coming for more than just our refreshing and cool evenings; it’s coming for our memory, for our health, and for our children's health. What once was a basic, restorative human need will become a luxury, as heat waves creep into our bedrooms and linger well past dusk. Night after night, the body will struggle to cool itself, tossing us into shallow, fragmented sleep. Over time, this chronic sleep deprivation will chip away at our immune systems, amplify stress hormones, and undermine cardiovascular health.
For the most vulnerable children, the elderly, and those with chronic illnesses, this isn’t just about discomfort. It’s also about survival, dignity, and memory. And in communities already burdened by social and economic pressures, the simple act of closing one’s eyes will carry hidden risks, shifting sleep from a sanctuary of rest into a battleground against relentless heat.
But we can do something about that.
So the question is, what should we do? We need to redesign, reimagine, and stop seeing climate resilience as an abstract concept. Climate resilience is personal, neurological, and evidently a key part of the future of our minds. If sleep is the brain’s guardian, and temperature is sleep’s gatekeeper, then climate change is the thief in the night. And we should be acting to stop it, because climate resilience does not emerge passively. It’s something we must design for.
So how are you rethinking architecture in a warming world?
Hauwa Busari is an MPhil student at the University of Cambridge, specialising in sustainable architecture and neuroscience to design environments that foster mental health and resilience, particularly for vulnerable communities. Having grown up in Bonny Island, Port Harcourt, and witnessing firsthand the challenges of access to clean water in areas impacted by oil pollution, she is deeply committed to creating climate-resilient, people-centered design solutions that address environmental crises and support the well-being of local populations.