Q: In this task, you are given a text of many news articles seperated by special token "|||||". Your task is to summarize them.
Artificial lighting could be making us frail, withering muscles and making bones more fragile, according to a new study. 
  
 Researchers kept mice under a constant light for six months – a torture technique used by the security services around the world. 
  
 When the mice were examined, they were found to be suffering from muscle loss and the early signs of osteoporosis, while their immune system appeared as if it was reacting to an infection. 
  
 The bottom line, the academics said, was that the natural cycle of day followed by night matters to animals. 
  
 Professor Johanna Meijer, of Leiden University Medical Centre in The Netherlands, who led the research, said: “We used to think of light and darkness as harmless or neutral stimuli with respect to health. 
  
 “We now realize this is not the case based on accumulating studies from laboratories all over the world, all pointing in the same direction. 
  
 “Our study … showed that the absence of environmental rhythms leads to severe disruption of a wide variety of health parameters.” 
  
 However a paper about the study, published in the journal Current Biology, reported that the mice recovered after they were switched to natural light. 
  
 “The good news is that we subsequently showed that these negative effects on health are reversible when the environmental light-dark cycle is restored,” Professor Meijer said. 
  
 The researchers said that light exposure should be taken into consideration, particularly for elderly and vulnerable people. 
  
 About 75 per cent of the world’s population is exposed to light during the night and constant light exposure is common in intensive care units. The problem could also affect night-workers. 
  
 “Possibly this is not surprising as life evolved under the constant pressure of the light-dark cycle,” Professor Meijer said. 
  
 “We seem to be optimized to live under these cycles, and the other side of the coin is that we are now affected by a lack of such cycles.” ||||| Along with eating right and exercising, people should consider adding another healthy habit to their list: turning out the lights. That's according to a new study reported in the Cell Press journal Current Biology on July 14 showing many negative health consequences for mice kept under conditions of constant light for a period of months. 
  
 "Our study shows that the environmental light-dark cycle is important for health," says Johanna Meijer of Leiden University Medical Center in the Netherlands. "We showed that the absence of environmental rhythms leads to severe disruption of a wide variety of health parameters." 
  
 Those parameters included pro-inflammatory activation of the immune system, muscle loss, and early signs of osteoporosis. The researchers say that the observed physiological changes were all indicative of "frailty" as is typically seen in people or animals as they age. But there was some more encouraging news, too. 
  
 "The good news is that we subsequently showed that these negative effects on health are reversible when the environmental light-dark cycle is restored," Meijer says. 
  
 To investigate the relationship between a loss of the light-dark cycle and disease, Meijer and colleagues, including Eliane Lucassen, exposed mice to light around the clock for 24 weeks and measured several major health parameters. Studies of the animals' brain activity showed that the constant light exposure reduced the normal rhythmic patterns in the brain's central circadian pacemaker of the suprachiasmatic nuclei (SCN) by 70 percent. 
  
 Strikingly, the disruption to normal light and dark patterns and the circadian rhythm led to a reduction in the animals' skeletal muscle function as measured in standard tests of strength. Their bones showed signs of deterioration, and the animals entered a pro-inflammatory state normally observed only in the presence of pathogens or other harmful stimuli. After the mice were returned to a standard light-dark cycle for 2 weeks, the SCN neurons rapidly recovered their normal rhythm, and the animals' health problems were reversed. 
  
 The findings suggest that more care should be taken in considering the amount of light exposure people get, particularly those who are aging or otherwise vulnerable. That's important given that 75 percent of the world's population is exposed to light during the night. Constant light exposure is very common in nursing homes and intensive care units, and many people also work into the night. 
  
 "We used to think of light and darkness as harmless or neutral stimuli with respect to health," Meijer says. "We now realize this is not the case based on accumulating studies from laboratories all over the world, all pointing in the same direction. Possibly this is not surprising as life evolved under the constant pressure of the light-dark cycle. We seem to be optimized to live under these cycles, and the other side of the coin is that we are now affected by a lack of such cycles." 
  
 The bottom line, according to the researchers is "light exposure matters." 
  
 They say they now plan to perform more in-depth analysis of the influence of distorted light-dark cycles on the immune system. They'd also like to investigate possible health benefits to patients exposed to more normal conditions of light and dark. 
  
 ### 
  
 This research was funded by the Netherlands Organization for Scientific Research grant TOPGO. L.10.035 and by the Dutch Diabetes Research Foundation grant 2013.81.1663. 
  
 Current Biology, Lucassen et al.: "Environmental 24-hr Cycles Are Essential for Health" http://www.cell.com/current-biology/fulltext/S0960-9822(16)30497-3 ||||| OJO Images Ltd/Alamy Stock Photo 
  
 Eliane Lucassen works the night shift at Leiden University Medical Center in the Netherlands, beginning her day at 6 p.m. Yet her own research has shown that this schedule might cause her health problems. “It’s funny,” the medical resident says. “Here I am, spreading around that it’s actually unhealthy. But it needs to be done.” 
  
 Lucassen and Johanna Meijer, a neuroscientist at Leiden, report today in Current Biology1 that a constant barrage of bright light prematurely ages mice, playing havoc with their circadian clocks and causing a cascade of health problems. 
  
 Mice exposed to constant light experienced bone-density loss, skeletal-muscle weakness and inflammation; restoring their health was as simple as turning the lights off. The findings are preliminary, but they suggest that people living in cities flooded with artificial light may face similar health risks. 
  
 “We came to know that smoking was bad, or that sugar is bad, but light was never an issue,” says Meijer. “Light and darkness matter.” 
  
 Disrupted patterns 
  
 Many previous studies have hinted at a connection between artificial light exposure and health problems in animals and people2. Epidemiological analyses have found that shift workers have an increased risk of breast cancer3, metabolic syndrome4 and osteoporosis5, 6. People exposed to bright light at night are more likely to have cardiovascular disease and often don’t get enough sleep. 
  
 Yet drawing a direct link between light exposure and poor health has been difficult. Meijer’s group explored this relationship in mice by implanting electrodes in the part of the animals’ brains that controls their body clocks, to measure the activity of neurons there. The scientists then housed the mice in brightly lit cages for 24 weeks. 
  
 The animals had bedding to make nests, could move freely and were able to close their eyes when they slept. But sleeping mice couldn't avoid the light entirely, and still got about one-seventh of the light exposure that they did while awake. Overall, the animals were exposed to more light than they would get in a typical light–dark cycle. 
  
 In response, the mice’s neuronal activity patterns shifted, leaving cells in the brain’s pacemaker region pulsing irregularly. This loss of synchronization mirrors what happens in ageing brains. 
  
 The mice also adopted a 25.5-hour day, lost bone density and had weaker muscles, as measured by how strongly they could grip with their forelimbs. After the researchers restored darkness, the mice's neurons returned to their normal rhythms and the animals reverted to a 24-hour day. 
  
 Bright lights, big impact 
  
 The analysis takes an innovative approach to studying circadian biology in mice, says Richard Stevens, an epidemiologist at the University of Connecticut School of Medicine in Farmington who studies the effect of light on cancer. But he says that the findings may not apply to people. The bright lights foisted on the mice were more dramatic than the light–dark cycles that people would experience in real life, even in extreme situations. 
  
 “The next experiment ought to be something like 12 hours of light, 6 hours of dim light and 6 hours of dark. That would be the kind of exposure that humans would have,” Stevens says. 
  
 And disruption of the biological clock alone might not cause the health effects reported in the study, says Steven Lockley, a neuroscientist at Harvard Medical School in Boston, Massachusetts. Poor sleep and light itself can each affect health, so an altered circadian clock may not be to blame. 
  
 But Meijer says the study should be a warning to people who work in intensive-care facilities or long-term care facilities, and to shift workers — such as her former student, Lucassen. 
  
 An atlas of artificial light pollution released in June showed that two-thirds of the world’s population is exposed to light at night7. Also last month, the American Medical Association’s Council on Science and Public Health called for a reduction in bright artificial light, citing evidence that it may increase a person’s risk of developing cancer, diabetes and cardiovascular disease. 
  
 Meijer now plans to examine how light affects the immune system, and she wants to repeat her neuron-monitoring study with grass rats, which are active during the day (unlike standard lab mice). She remains fascinated by the circadian system. 
  
 “There is no other region of the brain we know so much about,” Meijer says. “It has been a beautiful model for neuroscience research. But only in the last five to seven years have we realized it is also essential for health.” |||||
A:
Roughly one-third of the globe can no longer see the Milky Way thanks to artificial light at night. The impact of light pollution has long been obvious, but scientists are now exploring the role of constant exposure to light on health, and a study in the journal Current Biology adds both good and bad news. Researchers in Holland say the absence of natural light-and-dark rhythms can lead "to severe disruption of a wide variety of health parameters"—including a loss of bone density. The conditions were extreme: They were studying mice subjected to constant artificial light for six months, which is a torture technique, notes the Independent. The good news, as delivered by researcher Johanna Meijer at Eureka Alert: "These negative effects on health are reversible when the ... light-dark cycle is restored." To study the impact of so much light, the team implanted electrodes in the parts of the brain that control circadian rhythms and observed neuron activity in the mice. Though they could make nests and move freely, they were unable to totally avoid the light while they slept, reports Nature. Certain cells began to pulse irregularly, they adopted a 25.5-hour day, and they lost both bone density and muscle strength, becoming more frail. After researchers gave them dark periods again, though, all systems normalized. How much of this can be applied to humans remains unclear, but Meijer says it should serve as a warning to people such as shift workers who have irregular hours. (Light at night even inhibits cancer drugs.)