As part of the Integrative Cardiac Health Project at Walter Reed Army Medical Center, researchers analyzed the sleep, activity and energy expenditures of 14 nurses who had volunteered for a heart-health program at the Walter Reed, where the nurses were employed. The program included nutritional counseling, exercise training, stress management and sleep improvement.
Each participant wore an actigraphy armband that measured total activity, body temperature, body position and other indices of activity and rest.
"When we analyzed our data by splitting our subjects into 'short sleepers' and 'long sleepers,' we found that short sleepers tended to have a higher BMI, 28.3 kg/m2, compared to long sleepers, who had an average BMI of 24.5. Short sleepers also had lower sleep efficiency, experienced as greater difficulty getting to sleep and staying asleep," said lead investigator Arn Eliasson, M.D.
Surprisingly, overweight individuals tended to be more active than their normal weight counterparts, taking significantly more steps than normal weight individuals: 14,000 compared to 11,300, a nearly 25 percent difference, and expending nearly 1,000 more calories a day—3,064 versus 2,080.
However, those additional energy expenditures did not manifest in reduced weight.
"We found so many interesting links in our data. It opens up a number of possibilities for future investigation," said Dr. Eliasson. "Primarily, we want to know what is driving the weight differences, and why sleep and weight appear to be connected."
He postulates that getting less sleep might disrupt natural hormonal balances—for example, reducing the amount of leptin, otherwise known as the satiety hormone—and could thereby cause those individuals to eat more. Stress may also play a role in both reducing the length and quality of sleep and increasing eating and other behaviors that may result in weight gain.
"Higher perceived stress may erode sleep. Stress and being less rested may cause these individuals to be less organized than normal weight individuals, meaning they would have to make more trips and take more steps to accomplish the same tasks. This might add to their stress and encourage other unhealthy behaviors like stress eating," said Dr. Eliasson.
"It would be fascinating to know the results of a carefully designed study that controlled for the many influences on weight gain, while varying sleep parameters and measuring hormonal mediators of appetite and metabolism," said Dr. Eliasson. "We are planning further studies to evaluate the role of stress in sleep and metabolism."
Keely Savoie | EurekAlert!
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Researchers from the Department of Atomically Resolved Dynamics of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg, the University of Potsdam (both in Germany) and the University of Toronto (Canada) have pieced together a detailed time-lapse movie revealing all the major steps during the catalytic cycle of an enzyme. Surprisingly, the communication between the protein units is accomplished via a water-network akin to a string telephone. This communication is aligned with a ‘breathing’ motion, that is the expansion and contraction of the protein.
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Two research teams have succeeded simultaneously in measuring the long-sought Thorium nuclear transition, which enables extremely precise nuclear clocks. TU Wien (Vienna) is part of both teams.
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Researchers from Chalmers University of Technology have demonstrated a detector made from graphene that could revolutionize the sensors used in next-generation space telescopes. The findings were recently published in the scientific journal Nature Astronomy.
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A supersolid is a state of matter that can be described in simplified terms as being solid and liquid at the same time. In recent years, extensive efforts have been devoted to the detection of this exotic quantum matter. A research team led by Tilman Pfau and Tim Langen at the 5th Institute of Physics of the University of Stuttgart has succeeded in proving experimentally that the long-sought supersolid state of matter exists. The researchers report their results in Nature magazine.
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A team headed by Prof. Steve Albrecht from the HZB will present a new world-record tandem solar cell at EU PVSEC, the world's largest international photovoltaic and solar energy conference and exhibition, in Marseille, France on September 11, 2019. This tandem solar cell combines the semiconducting materials perovskite and CIGS and achieves a certified efficiency of 23.26 per cent. One reason for this success lies in the cell’s intermediate layer of organic molecules: they self-organise to cover even rough semiconductor surfaces. Two patents have been filed for these layers.
Perovskite-based solar cells have experienced an incredibly rapid increase in efficiency over the last ten years. The combination of perovskites with classical...
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