The science of napping: Study finds that long naps are associated with an increased risk of obesity

Is napping a secret weapon for better health? For decades, this question has drawn mixed opinions among scientists, but one thing is certain: a midday nap affects the functioning of our bodies.

In a recent study published in the scientific journal Obesity, a team of Spanish scientists looked at the issue of napping. Their findings shed new light on the relationship between the duration — and location — of napping and various metabolic markers, including obesity.

The study was conducted with more than 3,000 Spaniards from Murcia.

It was found that those who took a long nap — more than 30 minutes — had a body mass index — a measure of body weight relative to height — that was 2% higher than those who didn’t sleep.

They also had a 23% greater risk of obesity and a 40% greater risk of metabolic syndrome – a group of medical conditions that increase the risk of cardiovascular disease.

On the other hand, people who took short naps — less than 30 minutes — had a 21% lower risk of developing high blood pressure.

Long naps are associated with increases in body mass index, metabolic syndrome, triglycerides, glucose and blood pressure,” says Marta Garaulet, study author and professor of physiology at the University of Murcia, Spain.

“In contrast, when naps are short, we see that they are associated with a lower likelihood of developing high blood pressure, so naps become protective in a way.”

the study He concluded that the duration of the nap should be considered “obesity-related,” but the results only refer to “associations,” Garaulet explained, not to formal cause and effect.

In other words, the researchers made “related” links between people who, for example, take long naps and have a higher risk of obesity, but that doesn’t necessarily mean that those people are overweight because they take long naps. Nor do they take long naps because of their weight.

Culture and naps

Last year, Garaulet conducted another UK Biobank study of 450,000 people and found 127 genetic variants associated with napping: “The more napping genes, the higher the frequency of napping,” Garaulet told Euronews Next, “which will help explain why you can’t Some people are on naps. Take a nap.”

a I’m studying English – unlike the Spanish study – it used a statistical technique used in genetic research to investigate causal relationships between risk factors and health outcomes, called Mendelian randomization. This technique allowed Garaulet’s team to identify “possible causal relationships between more frequent daytime naps and increased blood pressure and waist circumference.”

The Spanish results are less conclusive because they did not use statistical technology. However, they offer new perspectives on napping.

The Spanish scientist said that the British study was conducted on a population with an average age of 60 years, “and since napping is not a habit of that culture.” So she was curious to see what was happening in a sample of young adults, with fewer illnesses, but also in a country where there is a strong napping culture and warm temperatures.

Heat was relevant because previous studies showed that napping genes are activated by heat.

“Summer temperatures activate PER3, which is the clock gene that initiates napping,” Garaulet said, which explains why Mediterraneans have a greater propensity to take naps in the middle of the day than northerners.

Some people don’t have the napping genes, he explained, “However, if we do get it, this napping gene can be activated in warmer regions, and we’ll want to sleep during the day.”

The Spanish results refined those from the Bank of England, and Garaulet was not only able to assess the more subtle aspects of daytime sleep episodes—namely, how the duration of naps affected the health of the individuals assessed—but also where the subjects slept affected the benefits. health.

“There is a positive association between short naps and improved blood pressure, especially if you sleep in an armchair or sofa instead of lying in bed,” Garaulet said.

He explained that it did not appear that the intention was for humans to make large changes in posture throughout the day, as this could increase blood pressure.

In line with her findings linking obesity to long naps, Jaraulet, a visiting professor at Harvard University, recently published another study which concluded that people who take long naps are more likely to alter the rhythm of an enzyme called lipase, which plays a critical role in digestion and metabolism. dietary fat.

Napping makes better workers

According to Garaulet, understanding the science behind napping can help recommend new methodologies to improve worker performance.

Previous studies revealed that short naps are associated with better working memory, as well as better performance and attention, particularly in sleep-deprived individuals, but the long-term effects of regular naps on chronic disease risk remain controversial.

“That’s why this is an interesting topic, which will help to understand whether or not naps should be recommended to get all these benefits at work, but more research is needed,” says Garaulet.

To get conclusive results about the metabolic effects of napping, scientists must conduct randomized crossover studies, Garaulet says, which entail experiments in which the same individuals are made to take naps but also refrain from them.

“The problem with these studies is that they can only be done in the short term, so you can look at the acute effects of napping, but not the effect on overall health.”

Acute effects refer to short-term changes or responses that appear after a specific intervention or exposure, such as an improvement in memory after a short nap.

To make conclusions about metabolic risk or obesity, researchers need several months with the same people, “and you can’t have someone who never naps, or who doesn’t have the genes to nap, or who takes naps every day or (is) who takes naps, even He doesn’t take a nap for six months,” he said.

However, while randomized crossover studies can be challenging to conduct, previous long-term studies have demonstrated the health benefits of napping. In 2007, one A study conducted by the Harvard School of Public Health suggested that napping contributed to lower rates of heart disease in Mediterranean countries.

The study followed more than 23,000 people for six years and showed that regular napping can reduce deaths from heart disease by 37%, which is a benefit of the same magnitude as that associated with lowering cholesterol, eating a healthy diet or exercising. of physical exercise.

Modern lifestyles have greatly influenced the frequency, duration, and timing of sleep episodes, and while research on napping may not provide conclusive evidence, there is an overwhelming amount of scientific literature supporting the idea that nothing is more important to sleep. Our health, happiness and productivity from a good night’s sleep.