Rising night-time temperatures driven by climate change are quietly eating into people's sleep worldwide, with the average person now losing over 50 hours a year, a new analysis has found. Across nearly every city out of over 1,300 analysed, the amount of temperature-related sleep loss linked to climate change has at least doubled since the early 1970s. In the early 1970s, people living in an average city of 500,000 residents lost about 46 hours of sleep per year due to night-time heat; by the 2020s, that rose to about 50 hours.

Climate change is elevating nighttime and daytime temperatures worldwide, affecting a broad continuum of behavioral and health outcomes. Disturbed sleep is a plausible pathway linking rising ambient temperatures with several observed adverse human responses shown to increase during hot weather. This systematic review aims to provide a comprehensive overview of the literature investigating the relationship between ambient temperature and valid sleep outcomes measured in real-world settings, globally. We show that higher outdoor or indoor temperatures are generally associated with degraded sleep quality and quantity worldwide. Although we identify opportunities to strengthen the state of the science, limited evidence of fast sleep adaptation to heat suggests rising temperatures induced by climate change and urbanization pose a planetary threat to human sleep, and therefore health, performance, and wellbeing.

Climate change has doubled the amount of sleep people lose annually due to warming nights over the past 50 years, a new analysis reveals. Between 2020 and 2025, the average person across 1,338 cities worldwide is losing approximately 56 hours of sleep per year due to high nighttime temperatures. Of this total, about six hours are directly attributable to human-caused global warming.

Overall, higher temperatures were significantly associated with an increased risk of sleep insufficiency. For each 10 °C increase of daily mean temperature at lag 0 d, the odds of sleep insufficiency increased by 20.1% (95% confidence intervals (CI): 19.9% to 20.3%). For each 10 °C increase in temperature (lag 0 d), total sleep duration decreased by 9.67 minutes (95% CI: 9.60 to 9.74). Notably, we projected 10.50% more cases of sleep insufficiency by the end of the 21st century under the high-emission scenario (SSP5-8.5) compared to the historical period. As the climate warms, we predicted an increase in sleep deprivation and a decrease in sleep duration throughout this century.

Global accelerometer data showed that each 1°C rise in night-time temperature reduced sleep by approximately 5–10 minutes, with older adults and women most affected. Very hot nights (>30°C) cut sleep by about 14.1 minutes, and nights above 25°C increased insufficient sleep (<7 hours) by about 3.5 percentage points. Large-scale investigations using wearable devices and survey data have demonstrated that each 1°C rise in night-time temperature reduces sleep duration by 7–14 minutes, with greater losses in vulnerable groups such as the elderly and low-income populations. The congruence between occupational and community-level findings suggests that heat is a universal risk factor for sleep loss.

For each 10 °C increase in ambient temperature, the odds of sleep insufficiency increased by 20.1%, while total sleep duration decreased by 9.67 minutes, with deep sleep declining the most (by 2.82%). Projections under the unrestricted (SSP5-8.5) greenhouse gas emission scenario suggest that by the end of the century, sleep insufficiency could rise by 10.50%, with an annual loss of 33.28 hours of sleep per person. By the end of the 21st century under the high-emission scenario (SSP5-8.5), we projected 13 hours more light sleep loss, 12 hours more deep sleep loss, and 6 hours more dream sleep loss compared to the historical period.

Across nearly every city analyzed, the amount of temperature-related sleep loss linked to climate change has at least doubled since the early 1970s. To estimate how climate change is affecting sleep in cities globally, Climate Central applied an established relationship between nighttime temperature and sleep to both observed and counterfactual temperatures — or the temperatures that would have occurred in a world without carbon pollution. We analyzed two time periods: 2020 to 2025, and a historical period in the early 1970s. Although the amount of temperature-related sleep loss due to climate change is relatively small, it has roughly doubled globally — from about two hours per year in 1970–1975 to about five hours per year in 2020–2025. The climate change-linked portion of this sleep loss has at least doubled since the early 1970s in nearly every city analyzed (1,335 of 1,338).

The present systematic review shows that higher outdoor or indoor ambient temperatures, expressed either as daily mean or night-time temperature, are negatively associated with sleep quality and quantity worldwide. The negative effect of higher ambient temperatures on sleep is stronger in the warmest months of the year, among vulnerable populations and in the warmest areas of the world. This result appears consistent across several sleep indicators and across different geographic regions.

The team says their findings suggest that by the year 2099, suboptimal temperatures may erode 50 to 58 hours of sleep per person per year. The study suggested that on very warm nights (greater than 30 degrees Celsius, or 86 degrees Fahrenheit), sleep declines an average of just over 14 minutes. The likelihood of getting less than seven hours of sleep also increases as temperatures rise.

Using data from 765,000 U.S. survey respondents from 2002 to 2011, coupled with nighttime temperature data, we show that increases in nighttime temperatures amplify self-reported nights of insufficient sleep. ... The results of estimating Eq. 1 indicate that a +1°C deviation in nighttime temperatures produces an increase of approximately three nights of insufficient sleep per 100 individuals per month. ... On average, we project that climate change may cause approximately 6 additional nights of insufficient sleep per 100 individuals by 2050 and an excess of approximately 14 nights per 100 individuals by 2099. ... Our analysis of historical data demonstrates a robust link between atypical nightly temperatures and insufficient sleep that is largest during the summer and among lower-income individuals and the elderly.

The study by Climate Central, a non-profit that researches effects of climate change, analysed 1,338 cities worldwide and found that temperature-related sleep-loss linked to climate change has at least doubled since the early 1970s. Between 2020 and 2025, the average person globally lost nearly 56 hours of sleep annually because of high nighttime temperatures, with more than one-tenth of that loss directly linked to climate change.

The temperature-related sleep loss linked to climate change has at least doubled since the early 1970s, a new study conducted across all 1,338 major global cities has found. The analysis by Climate Central also shows that over the last five years, the average person globally lost nearly 56 hours of sleep due to high temperatures. More than 10 per cent of that sleep loss was attributed to climate change, primarily caused by burning fossil fuels like coal, oil, and gas, and cutting down forests. This is the first analysis to directly quantify the number of hours of sleep lost due to climate change, combining cutting-edge research on the effects of temperature on sleep with the latest attribution science.

Higher nighttime temperatures are linked to shorter sleep times and lower sleep quality, especially for people with chronic health conditions, lower socioeconomic status, or those living on the West Coast, according to a new USC study. Researchers estimate that by 2099, people could lose up to 24 hours of sleep each year due to heat, highlighting the potential impact of climate change on sleep health. They found that a 10-degree Celsius increase in daytime temperature was associated with 2.19 minutes of lost sleep, while a 10-degree nighttime temperature increase was associated with a loss of 2.63 minutes.

This study included 14,232 adults with 12,531,244 nights of sleep duration and onset measurements and 8,134,295 sleep continuity and stage measurements in the continuous U.S. We found that a 10 °C increase of the daytime and nighttime temperature anomalies was associated with a decrease of 2.19 (95% Confidence Interval (CI): 2.09, 2.29) and 2.63 (95% CI: 2.51, 2.75) minutes of total sleep time, respectively. We project 8.5–24.0 additional hours of sleep reduction could occur per person-year in different climate zones by 2099 compared to 1995–2014.

Across more than 1,300 cities, climate change has at least doubled temperature-related sleep loss since the early 1970s, showing that the impacts of fossil fuel-driven warming extend beyond extreme weather to undermine one of the most fundamental requirements for human health, said Kristina Dahl, Climate Central’s VP for science. Globally, the report found that the average person lost nearly 56 hours of sleep every year during 2020–2025 because of high night-time temperatures, with more than 10% of that loss directly attributable to climate change caused primarily by fossil fuel emissions and deforestation. The study also found that climate-related sleep loss has at least doubled since the early 1970s across all 1,338 major cities analysed worldwide.

Using data from 765,000 U.S. survey respondents from 2002 to 2011, coupled with nighttime temperature data, we show that increases in nighttime temperatures amplify self-reported nights of insufficient sleep.

According to the analysis, people in many parts of southern India are losing between 78 and 91 hours of sleep every year because of hot nights. Of this, eight to nine hours annually can be directly linked to climate change, making India one of the countries most affected by warming-driven sleep disruption. ... Researchers found that across all cities studied, climate change has at least doubled heat-related sleep loss since the early 1970s. Globally, an average person lost nearly 56 hours of sleep every year because of nighttime heat between 2020 and 2025. Around six of those lost hours were directly linked to climate change, accounting for just over 10 per cent of the total sleep loss.

A new analysis by Climate Central has found that climate change linked sleep loss has more than doubled since the early 1970s across 1,338 major cities and India is among the worst affected. Researchers combined medical studies that explain how temperature affects sleep with climate attribution science. It then measures how much of today's warming is driven by human activities, particularly the burning of fossil fuels. The study covered 107 Indian cities and found that warmer nights are disrupting sleep across the country, with southern Indian cities among the worst affected, losing 78 to 91 hours of sleep every year due to high night time temperatures.

However, research shows that when nighttime temperatures exceed 25°C (77°F), people are 3.5% more likely to sleep less than seven hours. ... The One Earth study found that individuals living in already warm climates lose even more sleep per degree of temperature increase compared to those in cooler environments. Rather than building resilience, people in hotter regions become increasingly vulnerable to sleep loss as temperatures rise. ... Sleep affects nearly every aspect of well-being, both physiological and psychological, and climate change is emerging as a significant driver of sleep disruption through rising nighttime temperatures.

As temperatures rise due to climate change, our sleep is becoming shorter and more disrupted. Research shows the impact on our sleep is already measurable. Our 2023 study of 375 Australian adults found people lost 12 minutes per night on the hottest nights compared with the coldest (31°C vs 0.4°C overnight temperatures across the year). Globally, scientists predict we could lose 50–58 hours of sleep annually per person by the end of the century if warming continues unchecked. ... These findings highlight that climate change is not only about extreme weather events but also about subtle, chronic impacts such as reduced sleep duration and quality.

The main finding is that anomalous increases in nighttime temperature by 1 degree Celsius translate to three nights of insufficient sleep per 100 individuals per month. To put that in perspective: If we had a single month of nightly temperatures averaging 1 degree Celsius higher than normal, that is equivalent to 9 million more nights of insufficient sleep in a month across the population of the United States today.

A new global analysis by Climate Central has found that climate change has at least doubled temperature-related sleep loss in nearly every major city worldwide since the early 1970s, highlighting a growing but often overlooked public health consequence of global warming. The study, which analyzed 1,338 major cities across the globe, estimates that the average person lost nearly 56 hours of sleep annually between 2020 and 2025 due to high ambient temperatures. More than 10% of that sleep loss was directly linked to climate change. The study concludes that climate change has at least doubled heat-related sleep disruption in nearly every one of the 1,338 cities examined since the early 1970s.

Minor et al. (2022) provided one of the first large-scale quantifications of the relationship between nighttime temperatures and sleep duration using wearable device data. The study reported that unusually warm nights were associated with reduced sleep, and these temperature–sleep response functions have subsequently been used by other researchers to estimate heat-related sleep loss. Climate Central’s 2025 analysis explicitly states that it applied the published spline coefficients from Minor et al. (2022) to daily minimum temperature data to estimate climate change–attributable sleep loss since the early 1970s.