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Study changes in the brain during sleep deprivation
Lack of sleep is associated with a variety of health complaints, but also provide therapeutic uses of sleep deprivation. The basis for this are changes in the brain that occur during sleep deprivation. Researchers at Forschungszentrum Jülich have shown in a recent study, together with researchers from the German Aerospace Center (DLR), which molecular changes in the human brain are caused by unusually long periods of waking. The researchers published their results in the journal "Proceedings of the National Academy of Sciences" (PNAS).
Sleep disorders are a widespread problem that affects around 80 percent of employees in Germany, according to a recently published DAK study. The consequences of sleep deprivation can be far-reaching. Thus, a relationship with diabetes, heart attacks and strokes is proven. Sleep deprivation, however, according to the research team from Jülich is also "a quick, but only temporary effective remedy for depression." The effect is probably based on the molecular changes in the brain. Therefore, the scientists in their current study have examined this in detail.
Lack of sleep shows significant effects in the brain. (Image: pathdoc / fotolia.com) Lack of sleep with different effects on performance
For the study, 15 healthy male volunteers initially had to stay awake for 52 hours at a time and were then measured at the Jülich PET Center. This was followed by a transfer to DLR, where the participants were able to sleep under supervision for 14 hours, according to the Research Center Jülich. During the waking time, the subjects completed several performance tests, for example on reaction time and memory. Because lack of sleep can significantly affect performance. The tests showed that some participants had "extreme, sometimes second-long dropouts" as a result of their lack of sleep, while others barely noticed a drop in performance. The latter could benefit from their predisposition in occupations in which people regularly have to deliver flawless performance under sleep, the researchers write.
Sleep deprivation increases the number of available A1 adenosine receptors
The measurement of the changes in the brain was carried out by means of a so-called positron emission tomography (PET). It became clear "that the number of available A1 adenosine receptors increases due to sleep deprivation," reports study leader PD Dr. med. David Elmenhorst from the Jülich Institute of Neuroscience and Medicine (INM-2). Due to the subsequent recovery sleep, however, the number of available receptors has returned to normal levels. The A1 adenosine receptors, according to the researchers take over important functions in terms of sleep urgency, which is increasing with increasing sleep deprivation.
Regulation of sleep urge
The receptors are built into the cell wall as a kind of receptor, so that the messenger can dock adenosine, whose signal transmits the receptors into the cell's interior. This will shut down the cells in their activity. Whereas the concentration of adenosine used to be decisive for the onset of sleep urgency during long periods of wakefulness, researchers today are more of the opinion that the A1 receptors also play a role here. Because the adenosine concentration fluctuates practically every second, while the number of free receptors change much slower and thus better suited for a kind of "sleep memory", the scientists report.
Significant increase in receptor availability in "resistant" subjects
Subjects who were less susceptible to the 52-hour sleep deprivation showed significant differences in the availability of A1 adenosine receptors compared with those who had significant weaknesses in the performance test. "Astonishingly, in this seemingly resistant group of volunteers we could not find a constant value but a particularly strong increase in A1 receptor availability," emphasizes study author Dr. Elmenhorst. Subjects with a strong increase in receptor availability are more resilient to performance degradation and more successful in the tests. However, this increased value can not be equated with an exceptionally high concentration of receptor molecules, since the PET measurement only the net value - ie the free receptor molecules - detect, explain the researchers.
Low adenosine release causes high receptor availability?
Only the receptors, which were not blocked and available at the time of measurement, could be detected by PET measurement. However, the concentration of the receptor molecules plays here probably a minor role. "Our hypothesis is that the subjects for whom we have measured a particularly high A1 receptor availability produce relatively little adenosine and thus less inhibit the activity of the cells," explains Dr. med. Elmenhorst. According to the researchers, the receptors are also linked to the effect of caffeine. The active ingredient is attached to complex protein molecules and block them. Therefore, the subjects in the test series had to do without coffee and other awake-makers.
Therapeutic applications in depression
According to the researchers, the current study results are also important for clinical medicine. Because sleep deprivation forms a fast, but only temporary effective remedy for depression. Here "there are many efforts to extend the therapeutic effect of sleep deprivation in the treatment of depression." So far, however, there is the problem that one-time sleep is often sufficient to fall back into the depressive state, said Dr. med. Elmenhorst. Here, a "better understanding of the relationships between mood and adenosine regulation can help to optimize the design of watch therapies," the study director concluded. (Fp)