Hot Nights Are Stealing People’s Sleep, Researchers Say
Poinews.com – Climate change is disrupting sleep patterns worldwide, with rising nighttime temperatures linked to significant sleep loss. A recent study by Climate Central highlights how frequent “tropical nights”—when temperatures remain above 20°C overnight—have intensified over time, impacting people’s rest. Between 2020 and 2025, the global average saw a loss of nearly 56 hours of sleep per year, a figure equivalent to roughly seven nights of sleep, due to heat during the night.
Regional Disparities in Sleep Loss
The study analyzed over 1,300 cities and found that climate change has at least doubled temperature-related sleep loss since the early 1970s. The Middle East and Southeast Asia experienced the highest rates, with residents losing between 55 and 91 hours annually. In contrast, cities in northern Europe saw smaller losses, such as Edinburgh, Scotland, where people lost 21 hours, and Oslo, Norway, where the impact was minimal at 18 hours.
Impact Across Different Regions
While extreme heat affects cities globally, the effects vary widely. In southern Europe, Naples, Italy, recorded a 51-hour annual loss, while Athens, Greece, and Lisbon, Portugal, saw 45 and 40 hours respectively. Marseille, France, also reported a decline of 42 hours. In the northernmost regions, sleep loss still occurred, though to a lesser extent. For instance, Stockholm and Helsinki each experienced a 20-hour annual reduction.
Health Consequences of Sleep Deprivation
Sleep is critical for maintaining bodily functions during the day. When nighttime temperatures prevent recovery, the body remains under stress, leading to a range of health issues. Researchers note that poor sleep is associated with diminished mood, reduced cognitive performance, and lower productivity. It also affects cardiovascular and immune systems, compounding the risks of chronic health conditions.
“Sleep plays a major role in the correct functioning of the body during the day. Night-time is when the body is supposed to recover, but when temperatures fail to cool, this recovery does not happen and the body remains under strain.”
Factors Influencing Heat-Related Sleep Loss
Several factors contribute to the growing impact of heat on sleep. Urban areas, which act as heat islands, amplify nighttime temperatures, increasing the strain on residents. Additionally, age and income levels play a role. Adults over 65 face sleep loss more than twice as much as middle-aged individuals, while those in lower-middle-income countries experience nearly three times the effect compared to high-income regions. Women and people in hotter climates are also disproportionately affected, a trend expected to worsen as temperatures continue to climb.
