Health
When Thomas Edison tested the first light bulb in 1879, he could never have imagined that his invention could one day contribute to a global obesity epidemic.
Electric light allows us to work, rest and play at all hours of the day, and a paper published recently in Bioessays suggests that this might have serious consequences for our health and for our waistlines.
Daily or “circadian” rhythms including the sleep wake cycle, and rhythms in hormone release are controlled by a molecular clock that is present in every cell of the human body.
This human clock has its own inbuilt, default rhythm of almost exactly 24 hours that allows it to stay finely tuned to the daily cycle generated by the rotation of the earth.
This beautiful symmetry between the human clock and the daily cycle of the Earth’s rotation is disrupted by exposure to artificial light cycles, and by irregular meal, work and sleep times.
This mismatch between the natural circadian rhythms of our bodies and the environment is called “circadian desynchrony.”
The paper, by Dr. Cathy Wyse, working in the chronobiology research group at the University of Aberdeen, focuses on how the human clock struggles to stay in tune with the irregular meal, sleep and work schedules of the developed world, and how this might influence health and even cause obesity.
“Electric light allowed humans to override an ancient synchronisation between the rhythm of the human clock and the environment, and over the last century, daily rhythms in meal, sleep and working times have gradually disappeared from our lives,” said Wyse. “The human clock struggles to remain tuned to our highly irregular lifestyles, and I believe that this causes metabolic and other health problems, and makes us more likely to become obese.”
“Studies in microbes, plants and animals have shown that synchronisation of the internal clock with environmental rhythms is important for health and survival, and it is highly likely that this is true in humans as well,” Wyse added.
The human clock is controlled by our genes, and the research also suggests that some people may be more at risk of the effects of circadian desynchrony than others.
For example, humans originating from Equatorial regions may have clocks that are very regular, which might be more sensitive to the effects of circadian desynchrony.
Shiftwork, artificial light and the 24-hour lifestyle of the developed world mean that circadian desynchrony is now an inevitable part of 21st century life.
Nevertheless, we can help to maintain healthy circadian rhythms by keeping regular meal times, uninterrupted night-time sleep in complete darkness, and by getting plenty of sunlight during daylight hours.
Dr. Wyse believes that circadian desynchrony affects human health by disrupting the systems in the brain that regulate metabolism, leading to an increased likelihood of developing obesity and diabetes.
“The reason for the relatively sudden increase in global obesity in the developed world seems to be more complicated than simply just diet and physical activity,” she said. “There are other factors involved, and circadian desynchrony is one that deserves further attention.”
She added, “Our 24-hour society has come at the high price of circadian desynchrony. There are many factors driving mankind towards obesity but disrupted circadian rhythms should be considered alongside the usual suspects of diet and exercise.”
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Scientists are closer to establishing a definitive bacterial cause for the skin condition rosacea.
This will allow more targeted, effective treatments to be developed for sufferers, according to a review published in the Journal of Medical Microbiology.
Rosacea is a common dermatological condition that causes reddening and inflammation of the skin mostly around the cheeks, nose and chin. In severe cases skin lesions may form and lead to disfigurement.
Rosacea affects around 3 percent of the population – usually fair-skinned females aged 30-50 and particularly those with weak immune systems.
The condition is treated with a variety of antibiotics, even though there has never been a well-established bacterial cause.
A new review carried out by the National University of Ireland concludes that rosacea may be triggered by bacteria that live within tiny mites that reside in the skin.
The mite species Demodex folliculorum is worm-like in shape and usually lives harmlessly inside the pilosebaceous unit which surrounds hair follicles of the face.
They are normal inhabitants of the face and increase in number with age and skin damage – for example, following exposure to sunlight.
The numbers of Demodex mites living in the skin of rosacea patients is higher than in normal individuals, which has previously suggested a possible role for the mites in initiating the condition.
More recently, the bacterium Bacillus oleronius was isolated from inside a Demodex mite and was found to produce molecules provoking an immune reaction in rosacea patients.
Other studies have shown patients with varying types of rosacea react to the molecules produced by this bacterium – exposing it as a likely trigger for the condition. What’s more, this bacterium is sensitive to the antibiotics used to treat rosacea.
Dr. Kevin Kavanagh, who conducted the review, explained, “The bacteria live in the digestive tracts of Demodex mites found on the face, in a mutually beneficial relationship. When the mites die, the bacteria are released and leak into surrounding skin tissues – triggering tissue degradation and inflammation.”
“Once the numbers of mites increase, so does the number of bacteria, making rosacea more likely to occur. Targeting these bacteria may be a useful way of treating and preventing this condition,” said Dr. Kavanagh. “Alternatively we could look at controlling the population of Demodex mites in the face. Some pharmaceutical companies are already developing therapies to do this, which represents a novel way of preventing and reversing rosacea, which can be painful and embarrassing for many people.”
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