Study: Sleep timing may influence heart attack, stroke risks

Study Links Chronotypes to Heart Health Risks

A new study published in the Journal of the American Heart Association reveals that adults who identify as “night owls”—those naturally inclined to stay up late—tend to have lower cardiovascular health scores and an elevated risk of heart attacks or strokes. Researchers analyzed 14 years of data from the UK Biobank involving approximately 300,000 adults with an average age of 57. The study focused on chronotypes, which describe a person’s preference for morning or evening activity, and their connection to overall heart health. Night owls showed a 79% higher risk of poor cardiovascular health compared to those with intermediate schedules and a 16% increased likelihood of experiencing heart attacks or strokes. In contrast, morning people exhibited slightly better heart health, with the associations being more significant in women.

Participant Breakdown and Assessment Methods

Participants self-reported their chronotypes: about 8% identified as “definitely evening people” who stay up very late, 24% as “definitely morning people” who wake early and sleep earlier, and the largest group at 67% fell into an intermediate category. Heart health was evaluated using the American Heart Association’s Life’s Essential 8 score, which assesses factors like physical activity, diet, blood pressure, cholesterol, nicotine use, sleep patterns, weight management, and blood sugar levels. The study also tracked incidences of heart attacks or strokes over the follow-up period, highlighting how evening chronotypes correlated with worse outcomes in these metrics.

Reasons Behind the Findings and Expert Opinions

Lead researcher Sina Kianersi, Ph.D., from Brigham and Women’s Hospital and Harvard Medical School, explained that night owls often face circadian misalignment, where their internal clocks don’t align with natural light cycles or daily routines, leading to behaviors like poorer diet quality, smoking, and irregular sleep that harm cardiovascular health. Dr. Marc Siegel, Fox News senior medical analyst, noted that the body’s internal clock is designed for nighttime sleep, aiding processes like brain cleansing and stress reduction. Dr. Bradley Serwer, an interventional cardiologist, emphasized that while sleep is a key variable, cardiovascular disease stems from multiple factors, and high-quality restorative sleep should not be overlooked. These insights suggest lifestyle habits play a major role in the observed risks.

Study Limitations and Potential Implications

The study has limitations, including that it shows only an association between late-night tendencies and heart issues, not direct causation. It relied on self-reported data about schedules, habits, and health, which could introduce biases, and the UK Biobank participants are primarily White and healthier than the general population, limiting generalizability. Researchers noted that the findings could inform tailored medical interventions to prevent cardiovascular events. Dr. Serwer added that more research is needed to isolate sleep’s specific impact on heart health, underscoring the importance of quality sleep amid other contributing factors.

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