Why Nighttime Heat Is More Dangerous Than You Think
When temperatures refuse to drop at night, the health consequences multiply. So-called tropical nights—when temperatures never dip below 20°C—have become an increasingly common fixture across Europe, disrupting sleep and preventing bodies from recovering from daytime heat stress.
Southern European destinations sweltered through a record-breaking 23 tropical nights last summer, nearly three times the average of just eight, according to the EU’s Copernicus Climate Change Service. These sweaty, sleepless nights mean more than discomfort—they represent a serious public health threat.
“Nighttime temperatures are really important for our health because it’s the part of each day when we recover,” explains Dann Mitchell from the UK’s Met Office. When bodies can’t cool down overnight, health problems accumulate. People with cardiovascular conditions face increased strain. Sleep deprivation worsens mental health and impairs immune function.
Dr. Madeleine Thomson of Wellcome points out that deaths from heat stress are merely the most visible impact. The health burden extends to heart disease, pregnancy complications, and mental health crises—impacts that often go unrecognized as heat-related.
Urban areas face particular challenges. The “urban heat island effect” means cities remain significantly hotter than surrounding rural areas, with buildings and pavement absorbing heat during the day and radiating it back at night. This prevents the nighttime cooling that bodies desperately need.
Air conditioning helps people survive but brings its own problems: high energy costs, affordability barriers, and potential power blackouts when systems become overloaded during extreme heat events.
Solutions include adding green spaces that provide natural cooling, establishing cooling centers for those without home air conditioning, and implementing early warning systems that alert vulnerable populations before dangerous heat arrives.