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We’ve all read that dreaded headline: “Massive heart attack kills man while shoveling snow.” Is it true? Does winter increase the risks for having a heart attack, or could the sudden stress of physical activity in a couch potato be the cause? A recent study from Sweden of more than 280,000 patients suggests that cold air temperature can trigger a heart attack. The investigators found that the number of heart attacks per day was significantly higher during subzero Celsius temperatures compared to when it was warmer.
But winter brings many changes in addition to temperature. The hours of sunlight diminish, which can affect a variety of body functions including mood, body temperature, sleep/wake cycles, and secretion of hormones such as serum cortisol and melatonin. For example, seasonal affective disorder (SAD) is a well-established condition characterized by depression during the winter months, and is treated by exposing patients to a light therapy box emitting 10,000 lux of light each morning to simulate an earlier sunrise. Blood pressure is higher during the winter, as is cholesterol, upper respiratory infections, and the flu. Stroke mortality peaks in January, with a trough in September.
Interestingly, mortality is higher during the winter even in Los Angeles, where the winter temperatures remain mild. A study of over 220,000 deaths from Los Angeles County almost 20 years ago showed that the mean number of deaths was a third higher in December and January than between June and September. An increase in deaths peaked around the holiday season and then fell, raising the question of whether the stress of overeating or drinking during the holiday season, or perhaps sitting down to a turkey dinner with that disagreeable relative, might be a cause. Holiday hedonism is not the likely cause, because in Australia and New Zealand, the same winter influences on mortality occur during their winter months of June through August. In addition, sudden death also peaks in infants during the winter.
So, what can we conclude? Heart attacks, sudden death, and total mortality all increase during winter months, impacted by cold temperatures and other influences as well, such as shorter hours of daylight. My advice is to keep warm and continue your usual activities, diet, and medications. But be alert and check with your physician if you become aware of any new symptoms indicative of a change in health status. And stay happy! It’s good for your health!