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Showing entries tagged sleep.  Show all entries

October 23, 2011

To sleep or not to sleep


We've all been told that sleep has benefits, especially in college where sleep becomes more of a luxury than anything else. Sometimes there is just not enough time, but more often than not we are unwilling to give up the things we love just to have two more hours of sleep. But nonetheless I think it's safe to say that we have all experienced benefits from a good nights sleep. We need that extra energy so that the next day can suck it right out again. But why is it that we feel rested after sleeping for a decent amount of time?
Scientists have been trying to answer this question for a long time and from various angles. More recently researchers have suggested that a difference in the brain's ATP level might be linked to this phenomena. It's an interesting thought since ATP is the energy source of the body. But why the brain?
The brain only encompasses about 2% of our entire body mass. However it is one of the prime energy users. The brain utilizes about 20% of glucose and oxygen, both prime energy sources for the body. That means that 1/5 of the energy is being used by an organ that only comprises 2% of the body. So it does make sense to take a closer look at the brain when it comes to ATP levels.
A recent study published in the Journal of Neuroscience has shown that there are indeed differences in ATP levels during not only awake and sleep states but also the different sleep states and different brain areas. The results showed an ATP surge during the sleep state occurring at the onset hours of sleep.
So what does this surge do? Sadly enough it doesn't magically provide extra information for the next days exam, though that would be nice. The surge serves as nourishment to our brain, so that biosynthetic pathways can be restored. So in a way these surges of ATP are little helpers.
While working on this research, the researchers discovered that the ATP surges showed a correlation to the EEG NREM delta activity in spontaneous sleep. EEG NREM delta activity simply means that the waves generated by the NREM sleep period were of size delta and measured by an EEG. In the NREM period the neuronal activity drops and less energy is consumed which is exactly when the surge of ATP would occur.
Now how is this helpful to us other than just having gained some extra knowledge? The research shows the importance of sleep to our bodies' homeostasis. During the day we (hopefully) have high neural activity thus we are using up a lot of energy/ATP, but during the night we have low neural activity and thus use up less energy. So we get an energy surge at the onset of our sleep to take care of the restoration of biosynthetic pathways; at this point it is important that we are not using that energy surge for other purposes (like neural activity). So if we wake up to early because class might just be about to start, we have not been able to fully restore the biosynthetical pathways before our neural activity sets in again.
So you might argue that sleep is an important factor in test preparation as well. You might have studied as well as possible but if you did not let your body do its work over night, your biosynthetical pathways are not up to date.
So be kind and give your body a decent amount of sleep, that way you only have to worry about the actual studying.

Full article: http://www.jneurosci.org/content/30/26/9007.full
Posted by      Rebecca v. at 11:56 PM MDT

One Prick and you are Out


Isn't it crazy with one prick of anesthetics you can be out and then awaken hours later and have no recollection of what just happened? Sleep is like this too except, you have to close your eyes for a little then all sudden "poof", you awake to a morning sun. Sleep and anesthesia seem to be one in the same, but in reality they are not. Researchers in Canada measured the long field potentiation and coherence of cortical neurons in anesthetize and sleeping cats to investigate the differences.

Slow wave sleep (SWS) or what we call sleep is characterized by sleep slow oscillations, a characteristic of anesthesia. These oscillations form by cortical cells alternating between depolarizing and hyperpolarizing states. Depending on these oscillations neurons can either be active, a state of high synaptic activity or a silent state, low synaptic activity. Both aestheticize cats and sleeping cats were found in silent states but the amount of time aestheticizes cats were in the silent state differed.

Cats in SWS were found to have irregular slow waves or slow oscillations within each of the recorded cortical regions. When the anesthesia Ketamine- xylazine was injected into the cats, these regions showed consistent slow oscillations. These findings concluded that during SWS not all the brain regions are in silent states or inactive, so in sense, the brain still can processes information from the outside world. Opposite of that, aestheticize cats cannot process information because most the brain regions are in an inactive phase. So when a person receives anesthetics for surgery, they are not able to process that surgeons are cutting open their bodies, compared to a person who is able to wake up in the middle of the night because he or she processed that there might be a fire outside.

With the use of three different frequencies, regions of the brain could were investigated whether there are synchronous or non synchronous activities in the brain during the SWS and anesthesia. Aestheticized cats were found to have synchronous frequencies in contrast to nonsynchronous activities in SWS cats. These findings explain why a person can recall some of their dreams when they wake up compared to a person waking up from receiving an anesthetic. Because slow waves start to decrease as a person is about to wake up, there is a point in time where the active state is a little longer than a second, allowing a person to somewhat recall their dreams. While when someone is under anesthesia, the time in silent state is double compared to SWS. Synchronous brain activity allows for not time for regions of the brain to become consciousness during the transition from silent to an active state.

With these finding it hoped that further investigation of consciousness and unconsciousness could be understood. With many patients under comas for many days, months, and years, wouldn't it be a miracle if there was a way to wake them up?

Source:
Chauvette, Sylvain, Crochet, Sylvain, Tinofeev, Igor, Volgushev, Maxim. "Properties of Slow Oscillation during Slow- Wave Sleep and Anesthesia in Cats." The Journal of Neuroscience. 31 (2011)
http://www.jneurosci.org/content/31/42/14998.abstract
Posted by      Erika L. at 2:33 PM MDT
displaying most recent comments (4 ommitted) | Comments (7)
  Christina Uhlir  says:
Well then we have a pseudo-study it would seem: how do dogs, mice, and rats compare to cats in their sleep styles? Based on any criteria that can be traced across all four animals.
Posted on Mon, 24 Oct 2011 3:30 PM MDT by Christina U.
  Anna Gitarts  says:
Not sure if you trust Wikipedia, but: http://en.wikipedia.org/wiki/Sleep_%28non-human%29#Sleep_in_mammals . I can attest that my cat sleeps longer than 12 hours a day, though.
Posted on Mon, 24 Oct 2011 4:43 PM MDT by Anna G.
  Christina Uhlir  says:
Sometimes I think Wikipedia is a credible source. 12 hours seems like a tad of an underestimate for my fat cat. :)
Posted on Mon, 24 Oct 2011 5:27 PM MDT by Christina U.




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