Overview

• The analysis, published in Environment International, examined more than 14 million deaths from 1990 to 2018 across 178 cities in 44 countries, including 42 Spanish provincial capitals.
• Especially warm nights were associated with up to about a 3% rise in mortality, with a clear effect in most regions and only an indicative relationship in northern Europe.
• Scientists report that night-time heat impairs physiological recovery and sleep and may worsen cardiovascular, respiratory and neurological diseases, with urban heat islands intensifying exposure.
• In Spain, the highest fractions of deaths attributable to excess nocturnal heat were estimated in Granada (3.56%), Madrid (3.45%) and Córdoba (3.44%).
• The authors urge integrating night-time metrics into early-warning systems, expanding climate shelters and green spaces, ensuring adequate thermal conditions in homes and care facilities, and pursuing research on day–night interactions and event duration.