As global temperatures continue to rise, a silent public health threat is emerging, disrupted sleep. While the dangers of daytime heat — heat strokes, dehydration, and cardiovascular stress — are well documented, the effect of elevated nighttime temperatures on human sleep has largely gone unnoticed. A new study warns that Americans are already losing sleep due to rising temperatures, with the burden disproportionately falling on vulnerable populations.
Sleep is vital for mental and physical health, regulating everything from hormone balance to cognitive function. However, environmental stressors, particularly heat, can interfere with both sleep duration and quality. Recognizing the growing concern, researchers set out to quantify how heat exposure affects sleep patterns across the United States.
At the core of this research is the study “Impact of heat exposure on sleep health and its population vulnerability in the United States”, led by Jiawen Liao and colleagues. The work was published in Environment International in December 2025. Using data from 14,232 adults participating in the All of Us Research Program between 2010 and 2022, the team analyzed over 12.5 million nights of sleep alongside more than 8.1 million measures of sleep continuity and timing. Researchers matched these data with high-resolution meteorological records to calculate daytime and nighttime temperature anomalies, and then evaluated their impact on sleep duration, sleep onset, and continuity.
Climate Change Makes People Sleep Less
The study’s findings were stark. Every 10°C increase in daytime temperature anomaly was linked to 2.19 fewer minutes of sleep per night, while a 10°C nighttime anomaly led to a reduction of 2.63 minutes per night. Though these nightly losses may seem minor, they accumulate over time and may translate into serious long-term health consequences.
“This study highlights that the impact of climate change is not just felt during the day. Nighttime heat is quietly affecting millions of people’s ability to rest,” said Liao. “Even small nightly losses of sleep add up, potentially undermining health over months and years.”
“We found that sleep disruptions were not evenly distributed. Women, Hispanic communities, individuals with chronic illnesses, and people with lower socioeconomic status were most affected. This shows how environmental stressors can exacerbate existing social and health disparities,” Liao explain more.
Rima Habre, co author from University of Southern California noted, “Our analysis also revealed geographic differences. Residents in marine climate zones along the U.S. West Coast experienced sleep reductions almost twice as severe as those in other regions. Homes in these areas are often less adapted to extreme nighttime heat, leaving residents more vulnerable.”
The cumulative impact of rising nighttime temperatures is projected to grow. If global warming trends continue, Americans could lose between 8.5 and 24 hours of sleep per person per year by 2099 compared with baseline conditions from 1995–2014.
“These projections are not abstract numbers,” Habre emphasized. “They reflect the tangible effect climate change can have on daily life, affecting our productivity, health, and well-being.”
From mountains to oceans, delivered to you. Follow us on Lingkar Bumi WhatsApp Channel.
Effects of Sleep Deprivation
Beyond the immediate discomfort, heat-induced sleep disruption has significant health consequences. Chronic sleep deprivation has been linked to numerous mental health issues, including anxiety, depression, impaired cognition, irritability, and mood disorders. Physically, it increases the risk of obesity, type 2 diabetes, hypertension, cardiovascular disease, weakened immunity, and accelerated biological aging.
Habre added, “Addressing this problem requires both mitigation and adaptation. Expanding access to cooling technologies, improving home insulation, and urban planning designed to reduce nighttime heat are essential steps. Protecting sleep is as crucial as protecting against heat strokes or other visible climate impacts.”
This research emphasizes that climate change affects more than just extreme weather patterns or rising sea levels. It is silently eroding one of the most fundamental aspects of human health: restorative sleep. As Liao concluded, “Sleep is essential for physical and mental resilience. If we fail to protect it, we risk amplifying health disparities and chronic disease burdens across the nation.”
In summary, insufficient sleep caused by heat exposure threatens both mental and physical health. Psychologically, it contributes to anxiety, depression, impaired memory, and emotional instability. Physically, it elevates the risk of obesity, diabetes, hypertension, heart disease, weakened immune function, and accelerated aging. The study underscores that protecting sleep in a warming world is not a luxury but a critical public health necessity. (Sulung Prasetyo)
