- A study looks into the potential that one’s bedtime could be a risk factor for cardiovascular disease (CVD).
- The study’s authors discovered a link between the lowest risk of CVD and a bedtime of 10:00–10:59 p.m.
- Other bedtimes, according to the experts, could throw off the body’s intrinsic schedule.
Some previous studies suggest that not getting enough sleep can lead to cardiovascular disease.
However, there has been less focus on when we sleep and how this affects our cardiovascular health. According to a new study conducted by Huma Therapeutics, there may be a link.
According to the study, females who go to bed between 10 and 11 p.m. are less likely to get CVD than those who go to bed sooner or later.
Dr. David Plans, a top investigator, says:
“Our study indicates that the optimum time to go to sleep is at a specific point in the body’s 24-hour cycle, and deviations may be detrimental to health. The riskiest time was after midnight, potentially because it may reduce the likelihood of seeing morning light, which resets the body clock.”
The research was published in the European Heart Journal – Digital Health journal.
Circadian rhythm
“The body has a 24-hour internal clock, termed the circadian rhythm, that helps regulate physical and mental performance,” adds Dr. Plans. While our research cannot prove causation, the findings show that early or late bedtimes are more likely to upset the body clock, which could have negative effects for cardiovascular health.”
“The significance of circadian rhythms and the biological clock in human health is undeniable. “We all have a 24-hour clock that affects different parts of our bodies,” Dr. Atul Malhotra, a sleep medicine specialist at the University of California San Diego, told Medical News Today.
“But whether people go to sleep early or go to sleep late or something is kind of an individual characteristic,” Dr. Malhotra added.
“Some of us are early birds, and some of us are night owls, and that’s just the way it is. So to make a blanket statement that everybody should go to bed at X time is a bit silly, because, you know, it depends on your individual biology.”
While research has revealed that heart attacks tend to occur around 10:00 a.m., Dr. Malhotra informed MNT that it is not about the time shown on the clock on the wall. “After you wake up in the morning,” he explained, “is when the spike tends to occur based on [one’s] intrinsic clock. It’s not just the external clock that matters.”
Tracking bedtime
Between 2006 and 2010, the UK Biobank recruited a total of 88,026 participants, with 58 percent of them being female. They were between the ages of 43 and 70. The average age was 61.
Participants filled out questionnaires about their age, sex, sociodemographic status, amount of sleep they were used to, sleep disruptions, chronotype (night owl or early bird), and whether or not they smoked.
In addition, the researchers looked at the participants’ BMI, blood pressure, cholesterol levels, and diabetes status.
They then gave each study participant a wrist accelerometer, which allowed them to precisely trace the onset of sleep based on their lack of movement.
The researchers gathered preliminary sleeping data over the course of seven days and nights.
A 5.7-year follow-up period was used to track the progression of CVD in the participants.
Heart attack, heart failure, stroke, chronic ischemic heart disease, and transient ischemic attack were all considered CVD by the researchers.
The outcomes
During the study’s follow-up period, 3,172 participants (or 3.6 percent) developed CVD. The researchers discovered that women’s CVD risk differed from men’s.
Females who went to bed between 10:00 and 10:59 p.m. had the lowest CVD incidence.
Females who went to bed between 11:00 and 11:59 p.m. were 12 percent more likely than the rest of the group to develop CVD.
The researchers found that sleeping after midnight (25 percent) or before 10:00 p.m. was connected with the highest risk (24 percent ).
Males who went to bed before 10:00 p.m. were the only ones who had a strong link to an increased risk of CVD.
Speculating on the difference between the sexes, Dr. Plans says:
“It’s possible that how the endocrine system reacts to a disruption in circadian rhythm differs by sex.” Alternatively, because women’s cardiovascular risk increases after menopause, the higher age of study participants could be a confounding factor, indicating there may be no difference in the strength of the link between men and women.”
A variety of confounding factors, according to Dr. Malhotra, could impact the study’s conclusions. When it comes to the apparent link between early sleep onset and CVD, he said: “My guess is that some of the people who fall asleep earlier are sleep-deprived. They’re not getting enough sleep at night, so they tend to fall asleep early.”
“Sleep apnea is another prevalent disease,” Dr. Malhotra said, adding that it “may increase people’s cardiovascular risk.”
“While the findings do not show causality,” Dr. Plans concludes, “sleep timing has emerged as a potential cardiac risk factor — independent of other risk factors and sleep characteristics. If our findings are confirmed in other studies, sleep timing and basic sleep hygiene could be a low-cost public health target for lowering risk of heart disease.”
