Your Health

Research findings show an increase in the incidence of cardiovascular-related death occurring at nighttime

W. Gifford-Jones MD & Diana Gifford-Jones

May 13, 2022

BY W. GIFFORD- JONES MD & DIANA GIFFORD-JONES

John Travolta and Olivia Newton-John sang about romance in “Summer Nights,” the opening song in the hit movie, Grease. But now, at 68, he, more so than she, may want to watch out for a different kind of summer heat. New research shows that warm summer nights increase the risk of heart-related death among men in their 60’s.

The study involved analysis of 39,912 deaths due to cardiovascular disease in England and Wales between 2001 and 2015. After controlling for other factors, a rise of 1° Celsius (1.8° Fahrenheit) in summer nighttime temperature was associated with a 3.1% increase in the risk of death due to cardiovascular disease among men aged 60 to 64 years.

Replicating research results helps validate findings, and so a similar analysis was undertaken in a county within Washington State in the U.S. Here too, an increase of one degree in night time temperature resulted in a 4.8% increase in risk of heart-related death among men ages 60 to 64 years, although not older men above 65 years.

The research findings are concerning because they show an increase over recent years in the incidence of cardiovascular-related death occurring at nighttime rather than during daytime summer temperatures.

The details behind the study tell an interesting story. Why even think to study nighttime heat in mid-latitude settings? Is it not the soaring daytime heat in places known for scorching sun that deserve attention?

Haris Majeed, a PhD student with the Institute of Medical Science, Temerty Faculty of Medicine, at the University of Toronto, is the study’s lead researcher. His motivation was both academic and personal. As an early-career academic, he was pouring through his textbook readings, when he noted that although heart attacks occur at any time of day, most take place in the early morning hours while people are still in bed. Over the course of the year, the warmest months of June and July contain the highest rates of death from cardiovascular disease.

Majeed looked at places like Wales and Washington State because these places have strong seasonality. In effect, people in these places need to cope both with cold winters and hot summers. In these regions, too, many residents may not have air conditioning.

Why would men face a higher risk of heart attack with an increase in nighttime temperatures, and not women? Majeed speculates it might be due to men being more exposed to daytime heat, sweating more, and becoming dehydrated. This can lead to lower blood volume and increase the risk of blood clotting.

On the personal side, Majeed’s father recently underwent a bypass surgery and remains at high risk for health trouble when air temperatures go up. Contributing to the body of science that will help his father is a motivator like little else.

Majeed will need to do more work to test his theories.

In the meantime, as the northern hemisphere heads into the summer season, it would be prudent for people with cardiovascular concerns to take simple precautions. Keep well hydrated. Stay out of the sun during the hottest part of the day. Cool down with a quick cold shower before bed, and use a fan during the night when the heat is oppressive.

Going to sleep on a hot summer’s night should not be the most dangerous thing one does. But this research is highlighting two firm facts. One, cardiovascular disease is continuing to hold its place as a major killer, and two, air temperatures matter to human health.

Bottom line: keep cool when things heat up, especially at night.

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Written By W. Gifford-Jones MD & Diana Gifford-Jones

Dr. W. Gifford-Jones, MD is a graduate of the University of Toronto and the Harvard Medical School. He trained in general surgery at Strong Memorial Hospital, University of Rochester, Montreal General Hospital, McGill University and in Gynecology at Harvard. His storied medical career began as a general practitioner, ship’s surgeon, and hotel doctor. For more than 40 years, he specialized in gynecology, devoting his practice to the formative issues of women’s health. In 1975, he launched his weekly medical column that has been published by national and local Canadian and U.S. newspapers. Today, the readership remains over seven million. His advice contains a solid dose of common sense and he never sits on the fence with controversial issues. He is the author of nine books including, “The Healthy Barmaid”, his autobiography “You’re Going To Do What?”, “What I Learned as a Medical Journalist”, and “90+ How I Got There!” Many years ago, he was successful in a fight to legalize heroin to help ease the pain of terminal cancer patients. His foundation at that time donated $500,000 to establish the Gifford-Jones Professorship in Pain Control and Palliative Care at the University of Toronto Medical School. At 93 years of age he rappelled from the top of Toronto’s City Hall (30 stories) to raise funds for children with a life-threatening disease through the Make-a-Wish Foundation. Diana Gifford-Jones, the daughter of W. Gifford-Jones, MD, Diana has extensive global experience in health and healthcare policy. Diana is Special Advisor with The Aga Khan University, which operates 2 quaternary care hospitals and numerous secondary hospitals, medical centres, pharmacies, and laboratories in South Asia and Africa. She worked for ten years in the Human Development sectors at the World Bank, including health policy and economics, nutrition, and population health. For over a decade at The Conference Board of Canada, she managed four health-related executive networks, including the Roundtable on Socio-Economic Determinants of Health, the Centre for Chronic Disease Prevention and Management, the Canadian Centre for Environmental Health, and the Centre for Health System Design and Management. Her master’s degree in public policy at Harvard University’s Kennedy School of Government included coursework at Harvard Medical School. She is also a graduate of Wellesley College. She has extensive experience with Canadian universities, including at Carleton University, where she was the Executive Director of the Global Academy. She lived and worked in Japan for four years and speaks Japanese fluently. Diana has the designation as a certified Chartered Director from The Directors College, a joint venture of The Conference Board of Canada and McMaster University. She has recently published a book on the natural health philosophy of W. Gifford-Jones, called No Nonsense Health – Naturally!

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