A study of 150 adults found that aligning workout times with a person’s natural “chronotype”—whether they are an early bird or a night owl—leads to superior reductions in blood pressure and improved cardiovascular health.
Published in the journal Open Heart, the research involved teams from the UK and Pakistan. The investigators focused on participants aged 40 to 60 who already possessed at least one cardiovascular risk factor, such as obesity, physical inactivity, or high blood pressure.
Researchers tracked 150 adults with cardiovascular risks
Every participant entered the trial with a baseline of heart-related vulnerability. To categorize these individuals, the research team used a combination of detailed questionnaires and 48-hour core body temperature measurements.
These metrics established each person’s chronotype, the genetically determined tendency to sleep and wake at specific times. Most participants fell into one of two primary categories: “morning larks” or “night owls.”
How the 12-week trial measured biological clocks
The intervention spanned 12 weeks and required a rigorous commitment of 60 exercise sessions. Researchers randomly allocated participants to workout schedules that either matched their natural chronotype or contradicted it.
Workouts occurred in two strict windows: 8 a.m. to 11 a.m. for the morning group and 6 p.m. to 9 p.m. for the evening group. Maintaining this frequency—nearly five sessions per week—represented a substantial lifestyle shift for a group already struggling with physical inactivity.
Of the original group, 134 participants completed the full regimen. This included 70 early birds, 34 of whom exercised in the morning, and 64 night owls, 30 of whom worked out in the evening.
Across the study, blood pressure dropped more when workouts matched natural preferences
Heart risk factors, aerobic fitness, and sleep quality improved for all participants regardless of when they exercised. The data confirms that consistency in activity provides a baseline of health benefits for those with cardiovascular risks.
Greater reductions in blood pressure appeared in the matched group. These participants also saw more marked improvements in heart rate, aerobic capacity, and overall sleep quality compared to those whose schedules clashed with their biological clocks.
Fasting glucose levels were also recorded before the trial and three days after its conclusion to track metabolic changes. While both groups saw gains, the synchronization of exercise with the body’s internal clock acted as a force multiplier for cardiovascular recovery.
Why chronotype assessments could change patient care
Clinicians may find it advantageous to assess whether a patient is an early bird or a night owl before prescribing an exercise plan. This personalization could be especially effective for patients managing chronic hypertension or obesity.
Syncing physical activity with natural rhythms doesn’t just make a workout more pleasant; it appears to optimize the biological response to the stress of exercise. By timing activity to match peak wakefulness, patients may achieve better clinical outcomes with the same amount of effort.
How can someone determine their own chronotype?
In this study, researchers used 48-hour core body temperature monitoring and detailed questionnaires to categorize participants as either “morning larks” or “night owls.”
Does exercising at the “wrong” time still provide health benefits?
Yes. The study found that both the matched and mismatched groups experienced improvements in sleep quality, aerobic fitness, and heart risk factors over the 12-week period.