People will get maximum benefits of exercise only if exercise timing is aligned with individual chronotype in adults

Timing exercise to match body clock chronotype—the natural predisposition to morning or evening alertness—may lower cardiovascular disease risk among those who are already vulnerable, suggests research published in the open access journal Open Heart.
Aligning exercise timing with individual chronotype in adults at cardiovascular risk led to greater improvements in blood pressure, metabolic markers, autonomic function, aerobic capacity, and sleep quality compared to mismatched timing. The effect was most pronounced in systolic blood pressure and sleep quality, especially among those with hypertension and morning chronotypes.
Chronotype alignment boosted sleep quality and lowered risk factors, such as high blood pressure, fasting glucose, and "bad" cholesterol, more effectively than mismatched exercise timing, the trial results indicate.

The findings prompt the researchers to suggest that individual chronotype assessment should be included in exercise prescriptions for those who are at risk of cardiovascular disease.

Exercise lowers the risks of heart disease/stroke and diabetes, and whether someone is naturally a morning lark or a night owl—an innate disposition that affects sleep-wake patterns, hormone secretion, and energy availability across the day—influences exercise performance and adherence, explain the researchers.
Analysis of the experimental results showed that cardiovascular disease risk factors, aerobic fitness, and sleep quality improved in both groups after 12 weeks.

But matching exercise with chronotype produced larger improvements in blood pressure, autonomic function (involuntary bodily processes, including heart rate), aerobic capacity, metabolic markers, and sleep quality than mismatched exercise.

These improvements were especially noticeable in sleep quality—an increase of 3.4 compared with 1.2 points—and systolic blood pressure—the higher of the two numbers in a reading.

This fell by 10.8 mm Hg in those whose exercise sessions had been matched to their chronotype compared with a drop of 5.5 mm Hg among those whose exercise sessions had been mismatched.

The fall in systolic blood pressure was even larger among those who had high blood pressure to begin with: their systolic blood pressure fell by an average of 13.6 mm Hg compared with 7.1 mm Hg in those whose exercise sessions had been mismatched.

Although improvements were observed across both chronotypes, overall, the effects were larger among morning larks than among night owls.

Chronotype-aligned exercise timing in middle-aged adults at cardiometabolic risk: a randomised controlled trial, Open Heart (2026). DOI: 10.1136/openhrt-2025-003573