Sleep plays an important role in heart health. A study from Harvard Medical School, published in The Journal of the American College of Cardiology, shows that people with highly irregular sleep patterns have a significantly higher risk of developing cardiovascular disease.
Even small differences in bedtime can matter. If the timing of sleep varies by around an hour from day to day, the risk of heart disease and metabolic problems may increase by up to 50 percent.
The amount of sleep also matters. Research indicates that people who sleep less than six hours per night have about a 20 percent higher risk of experiencing a heart attack.
A study from February 2026, published in Circulation Reports, also found a link between short sleep duration and the heart rhythm disorder atrial fibrillation among people in their 50s.
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The body’s internal clock can be disrupted
According to National Geographic, the transition to daylight saving time can resemble a mild form of jet lag.
The body is regulated by a circadian rhythm that is influenced, among other things, by natural light.
When the time changes, the body’s internal clock no longer fully matches the surrounding environment.
Most people adjust to the initial fatigue after a few days, but researchers point out that the body may remain slightly out of sync for several months.
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Similar problems are seen among people who work night shifts or rotating schedules.
A study published in the Scandinavian Journal of Work, Environment & Health shows that they have about a 17 percent higher risk of cardiovascular disease.
A small change can have longer consequences
There has long been debate about whether daylight saving time should be abolished. Some research has previously suggested that heart attacks increase immediately after the time change.
However, a larger analysis published in JAMA Network Open in 2025, based on nearly 170,000 patient records, did not find a clear rise in cases immediately after the switch to daylight saving time.
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Still, when a single hour shifts the body’s daily rhythm for several months, it can lead to poorer sleep, higher stress levels, and elevated blood pressure.
Over time, these factors can increase the strain on the heart.
Sources: National Geographic, The Journal of the American College of Cardiology, Circulation Reports, Scandinavian Journal of Work, Environment & Health, and JAMA Network Open.
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