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why do we get sleepy at night

Well scientists aren t 100% sure about that! Some people say that it gives your body a chance to recuperate after a hard day, but the energy saved is only about 50 kcals for 8 hours sleep (about the same amount of energy in a slice of toast with no butter! ). I think there might be an evolutionary reason, traditionally humans couldn t do much at night because we don t have good night vision compared to lots of predators! Also, think about what would happen if we didn t sleep. Lack of sleep has serious effects on our brain s ability to function. Have you ever pulled an all-nighter?? and the after-effects: grumpiness, grogginess, irritability and forgetfulness. After just one night without sleep, concentration becomes more difficult and attention span shortens considerably.

Thanks for the good luck the operation went really well!! But I am pretty sore and groggy today! The pain killers and anesthetic are not making me feel good! I ve now got to wear a cast for 4 weeks booooo!!!
Scientists know we need sleep, but they don t know exactly why, and they ve been pretty clueless about how the brain decides when to sleep. Some of the mystery has been put to rest. A new study of mice finds that brain cells called astrocytes fuel the urge to sleep by releasing adenosine, a chemical known to have sleep-inducing effects that can be inhibited by. The longer a person or animal is awake, the stronger the urge to sleep becomes. This is known as sleep pressure. Prior studies pointed to adenosine as a trigger for sleep pressure. The chemical accumulates in the brain during waking hours, eventually helping to stimulate the unique patterns of brain activity that occur.

The new study found adenosine from astrocytes clearly regulates sleep pressure, said study team member Michael Halassa of Tufts University School of Medicine in Boston. It is the first time a non-neuronal cell in the brain has been shown to influence behavior, Halassa said. Unlike neurons, astrocytes do not fire electrical spikes, and they are often thought of as simply support cells. This research could lead to better drugs for inducing sleep when it is needed, and for staving off sleep when it is dangerous, said Merrill Mitler of the National Institute of Neurological Disorders and Stroke, part of the federally funded National Institutes of Health.

The research is detailed today in the journal Neuron. The scientists flipped a genetic switch in the mice to block the release of adenosine and other chemicals from astrocytes. The researchers then deprived the mice of sleep for short periods, and evaluated them with behavioral tests and by recording brain activity. Mice subjected to the genetic blockade exhibited less sleep pressure than control mice. Following sleep deprivation, they did not need as much compensatory sleep, and during the early phases of sleep, they had patterns of brain activity consistent with low sleep pressure. Further studies of the newfound sleep mechanism in mice could help reveal why people need sleep at all, the scientists said. How Long Can a Person Survive Without Sleep?

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