Warm summer nights may leave you tossing and turning in bed, but that could be the least of your worries. Just a slight rise in summer nighttime temperatures increases the risk of heart-related death for men in their 60s, a new study shows.
"Considering the growing likelihood of extreme summers in Western USA and the United Kingdom, our results invite preventive population health initiatives and novel urban policies aimed at reducing future risk of cardiovascular disease events," the authors wrote in the report published online March 28 in the BMJ Open.
For the study, the researchers analyzed data on nearly 40,000 heart-related deaths of men and women that occurred in England and Wales in June and July between 2001 and 2015. They also reviewed similar data on the deaths of 488 men in King County, Wash., and examined weather data from the regions.
After adjusting for other factors, a 1° Celsius rise (a 1.8° rise Fahrenheit) in the usual summer nighttime temperature in England and Wales was associated with a 3.1% increase in the risk of heart-related death among men aged 60 to 64, but not in older men or in women, the researchers said.
In King County, a 1° C rise was associated with a nearly 5% increased risk of heart-related death among men 65 and younger, but not in older men, according to the study.
The researchers noted there was a significant overall decline in heart-related deaths in both regions during the 15-year study period, notably during the summer months, due to medical advances.
Even so, a sizable residual risk remained, and rates of heart-related deaths in England and Wales remained more than 50% higher in adults aged 65 to 69 than in those aged 60 to 64, the findings showed.
The study authors said this is worrying because populous regions such as the ones included in the study have had a proportionate rise in nighttime rather than daytime summer temperatures in recent years.
The researchers said heat waves have been linked to heart problems, but noted little research has been done regarding age or gender.
Because this is an observational study, it can't establish causality, but its strengths included large population size data and strong national death and weather statistics, the authors said in a journal news release.
"The present findings should stimulate similar investigation of exposure and event rates in other populous mid-latitude to high-latitude regions," wrote Haris Majeed and colleagues. Majeed is with the Institute of Medical Science, Faculty of Medicine, at the University of Toronto in Canada.
The U.S. National Heart, Lung, and Blood Institute offers a guide to a healthy heart.
SOURCE: BMJ Open, news release, March 28, 2022