“Only 65% of adults in the U.S. regularly sleep the recommended seven hours per night, and there’s a lot of evidence suggesting that this lack of sleep is associated with cardiovascular disease in the long term,” said Anne-Marie Chang, associate professor of biobehavioral health and co-author of the work. “Our research reveals a potential mechanism for this longitudinal relationship, where enough successive hits to your cardiovascular health while you’re young could make your heart more prone to cardiovascular disease in the future.”
This study involved 15 healthy men between the ages of 20-35 years old who participated in an 11-day inpatient sleep study, during which they slept for up to 10 hours per night for the first three nights, then for the next 5 nights, their sleep was restricted to 5 hours per night that was followed by 2 recovery nights of up to 10 hours of sleep per night. Participants resting heart rates and blood pressure were measured every 2 hours during the day to evaluate the effects of the study sleep regime on cardiovascular health.
The researchers report that heart rate increased by nearly one heartbeat per minute (BPM) with each successive day of the study. The average baseline heart rate was 69 BPN and the average heart rate at the study conclusion on the second day of recovery was nearly 78 BPM. Findings also revealed that systolic blood pressure increased by about 0.5 mmHg per day, the average baseline reading was 116 mmHg and this reading increased to nearly 119.5 mmHg by the end of the recovery period.
“Both heart rate and systolic blood pressure increased with each successive day and did not return to baseline levels by the end of the recovery period,” Reichenberger said. “So, despite having additional opportunity to rest, by the end of the weekend of the study, their cardiovascular systems still had not recovered.”
“Sleep is a biological process, but it’s also a behavioral one and one that we often have a lot of control over,” Chang said. “Not only does sleep affect our cardiovascular health, but it also affects our weight, our mental health, our ability to focus and our ability to maintain healthy relationships with others, among many other things. As we learn more and more about the importance of sleep, and how it impacts everything in our lives, my hope is that it will become more of a focus for improving one’s health.”
It was noted that heart rate and blood pressure were measured at multiple times throughout the day which enabled the researchers to account for any effects that time of day might have on the readings. The researchers suggest that longer periods of sleep recovery may be required to recover from sleep loss that occurs over multiple consecutive nights, as 2 days were not enough in this study.
