We CAN believe that the secret to maintaining good youthful health lies in turning back time with “magical” potions and diets. But scientists now say we can do something much more practical (and promising) by targeting our internal clocks.
US researchers suggest that we can improve our physical and mental health – and even slow aging – by adopting daily habits that help keep our various internal clocks properly synchronized with each other so that they operate efficiently. optimal.
It has been known since the 1990s that the body has an internal molecular clock that operates on a daily cycle to regulate vital functions such as sleep, appetite and metabolism. This is called our circadian rhythm or clock.
But there is more than one clock. In fact, in recent years, researchers have discovered that we are full of internal timekeepers.
Circadian clocks are now thought to be present in almost every cell and tissue in our body, with a “master clock,” called the suprachiasmatic nucleus, in the brain.
American researchers suggest that we can improve our physical and mental health by adopting daily habits that help us keep our different internal clocks properly synchronized with each other.
It has been known since the 1990s that the body has an internal molecular clock that operates on a daily cycle to regulate vital functions such as sleep, appetite and metabolism.
The bad news is that as we age, our circadian timers can become increasingly out of sync with each other, according to a study from Northwestern University in the United States, published in the journal Chaos early this month. month.
It’s a bit like living in a house full of vintage wind-up clocks that all chime at different times. This can mean that vital systems regulating body and brain functions are not functioning in a healthy, synchronized way like they did when we were younger.
Research increasingly links this “circadian clock desynchronization” to serious problems such as cardiovascular disease, obesity, type 2 diabetes and cancer, North West scientists have warned.
Furthermore, the damage is not only physical, according to a study carried out by biologists from Cleveland State University in the United States.
In a review published last year in the journal Nature Reviews Neuroscience, they demonstrated that our circadian clock regulates crucial functions such as our body’s systems for repairing faulty DNA, as well as a vital maintenance process called autophagy , which rids our brain of damaged cells. .
The Cleveland researchers warned that circadian rhythms “are significantly affected by aging – and that this impairment may contribute to cognitive decline in the aging brain.”
They said circadian rhythms are “markedly disrupted” in patients with Alzheimer’s disease, as well as Parkinson’s disease, suggesting that out-of-sync clocks may be at least partly responsible for these conditions.
But they added that experiments on rodents with symptoms of dementia aimed at restoring the accuracy of their circadian clocks – by making them run on their appropriate daily schedules – improved the animals’ “cognitive performance” and increased their lifespans. .
A report published in February in the journal Nature Reviews Endocrinology suggests that if we can promote better circadian synchronization later in life, it can “effectively delay the aging process” because our bodies will function more efficiently.
So, is it really possible to improve the precision of our various biological clocks? Research is beginning to suggest some intriguing answers. The Northwestern University researchers pointed out that different circadian clocks rely on different external signals to set themselves each day.
The brain’s clock depends on sunlight, for example, while peripheral organs, like our liver, calibrate themselves based on meal times, said Dr. Yitong Huang, who led the study. .
Eating at the wrong times – like midnight meals – can be particularly damaging, she warned: “Giving your internal clocks mixed signals by eating at night – eating when your brain is about to rest – can confuse them and cause a misalignment between the internal clocks. .’
On the other hand, she said, eating breakfast first can actually signal our metabolism to set our clocks correctly at the start of the day.
Food consumption is a zeitgeber (time giver), says Dr. Kristin Eckel Mahan, associate professor at the University of Texas Center for Metabolic and Degenerative Diseases and lead author of the Nature Reviews report.
She cites laboratory studies where the timing of food intake has been shown to stimulate the synchronicity of the circadian clock.
Other research suggests that food can contribute significantly to keeping our internal clocks in sync, but only if we eat nearly a third less than the recommended amount, reducing our intake by a grand average of 2,000 calories per day for women and 2,500 for men to 1,400 and 1,750 calories respectively.
Studies on fruit flies have shown that reducing their food intake to 70 percent of their normal needs could extend their lifespan by up to 40 percent (the equivalent, in humans, of living up to 120 years).
Dr. Eckel Mahan explains that this effect is because calorie restriction improves the synchronization of our internal clock. It achieves this by optimizing the activity of biological clocks which help reduce harmful inflammation and protect brain cells from damage.
Another reason, she adds, is that dietary restrictions increase the efficiency of biological clocks that detect light – and daylight is one of the most important environmental influences when it comes to setting the rhythm of our daily clock. This can be especially important as we age.
The new study from Northwestern University highlighted that a common problem among older adults is that their body clock becomes less sensitive to the daily adjustment of daylight.
Such findings are consistent with the work of Russell Foster, professor of circadian neuroscience at the University of Oxford. Many studies show that as we age, the lenses of our eyes become less clear and the number of light receptor cells in our retina decreases, so we are less sensitive to light levels.
Professor Foster’s strongest advice is that we should actively go out and seek daylight to start our days – and set our internal clocks.
He says, “Get the morning light. This will strengthen your circadian drives.
He cites research conducted in nursing homes where patients were exposed to bright light every morning for several years. Not only did it reduce both cognitive decline and depressive symptoms, but it also improved their nighttime sleep and reduced their daytime sleepiness.
Still, he adds, sleeping less well as we age — because our aging internal clocks are more likely to get out of sync — is a problem that will trouble most of us.
“In midlife, there’s no point in looking at the sleep you had in your 20s and 30s as some sort of ideal,” he says. “We must accept that things change and adapt our habits.”
