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If you prefer to go to bed and wake up later – a sleep pattern known as a night owl – you may have a higher risk of type 2 diabetes and heart disease, a new study suggests. .
The night owls were more sedentary, had lower levels of aerobic fitness, and burned less fat at rest and when active than the first birds in the study. Night owls are also more insulin resistant, which means their muscles need more insulin to get the energy they need. according to research published Monday in the journal Experimental Physiology.
“Insulin tells muscles to be a sponge and absorbs glucose in the blood,” said senior study author Steven Malin, associate professor in the department of kinesiology and health. at Rutgers University in New Jersey.
“Think of it like water from a faucet: You turn on the water and a drop hits the sponge and is immediately absorbed,” says Malin. “But if you don’t exercise, work those muscles, it’s like having that sponge sit for a few days and get stiff. A drop of water won’t make it soft again. ”
Malin adds that if the type of sleep duration affects how our bodies use insulin and impacts metabolism, then being a night owl could be helpful in predicting disease risk. a person’s heart and type 2 diabetes.
“The study adds to what we know,” said Dr. Phyllis Zee, director of the Center for Sleep and Vascular Medicine at Northwestern University Feinberg School of Medicine in Chicago, who was not involved in the study.
“There is good evidence that sleeping late is associated with a higher risk of metabolic and cardiovascular disease,” said Zee, professor of neurology. “Several mechanisms have been proposed: insomnia, circadian rhythm deviations, eating later in the day, and greater exposure to morning and evening light, all of which have been shown to affect blood pressure. insulin sensitive.”
All humans have a circadian rhythm – an internal 24-hour body clock that regulates the release of the hormone melatonin to promote sleep and shuts down production for us to wake up. Our body clock also directs when we are hungry, when we feel most sluggish, and when we feel happy enough to exercise, among many other bodily functions.
Traditionally, sunrise and nightfall regulate human sleep-wake cycles. Daylight enters the eyes, travels to the brain, and sends out a signal that suppresses melatonin production. When the sun goes down, the body clock activates melatonin production again and a few hours later sleep will come.
Your individual type of sleep duration, thought to be genetic, can alter that natural rhythm. If you’re a born baby bird, your circadian rhythm releases melatonin much earlier than normal, helping you to be most active in the morning. In night owls, however, the body’s internal clock releases melatonin much later, making early morning sluggish and pushing peak activity and alertness into the afternoon and evening.
Experts say the chronological order of sleep can profoundly affect productivity, school performance, social functioning and lifestyle habits. Early birds tend to perform better at schooland be more active during the day, which may partly explain why studies have found they have a lower risk of cardiovascular disease, Malin said.
Types of evenings possible take more risksuse more tobacco, alcohol and caffeineand there are many possibilities skip breakfast and eat more later in the day. Additionally, research shows that “crop tops later have higher amounts of body fat located more in the stomach or abdomen, an area many health professionals say is detrimental to health.” ours,” Malin said.
The researchers classified 51 adults without heart disease or diabetes into morning or evening time patterns, based on their natural sleep and wake preferences. During the study, participants ate a controlled diet and fasted overnight while their activity levels were monitored for a week.
The research team determined Each person’s body mass, body composition and fitness level, and insulin sensitivity were measured. In addition, the researchers looked at how each person’s metabolism gets most of their energy, either through fat or carbohydrates.
“Fat metabolism is important because we think that if you can burn fat for energy, that will help your muscles to absorb glucose more sustainably,” says Malin.
Burning fat can promote endurance and more physical and mental performance during the day. On the other hand, carbohydrates are what the body uses for intense physical activity. Carbs are burned faster, which is why many athletes load up on carbs before a race or marathon.
The results of the trial showed that the birds initially used more fat for energy both at rest and during exercise than the night owls in the study, who consumed more carbohydrates. as a fuel source.
More research is needed to confirm the findings and determine if the metabolic differences are due to the type of time, or a potential deviation between the night owls’ natural preferences and their need to stay awake, Malin said. Wake up early due to the time prescribed by society. workplace and school.
People who are constantly out of sync with their innate body clocks are said to be in a state of “social plane lag”.
“This is not just about diabetes or heart disease,” says Malin. “It could point to a larger social problem. How do we help those who may be misdirected? Are we a society that forces people to behave in ways that actually put them at risk?