why sleep?

Discussion in 'Human Science' started by user41, Jan 22, 2014.

  1. user41 Registered Member

    please read and comment (what i have typed is my impression on the topic. critical views are welcome)

    experiments performed on mice indicate a tremendous increase in the number of neuronal connections over the course of the day, meaning, each "thought" or "decision" made, or things seen etc, are temporarily represented in the brain as the additional synapses created while perceiving them. research indicates that sleep actually prunes the useless synapses formed and returns the brain to a basal level so as to maintain its optimal activity for the next day(Source: Scientific American).

    there is evidence that our brains can partially shut different parts each time, meaning, some part of my brain could be asleep right now, even as i am typing this article out.

    probably, the additional synapses created form additional low resistance pathways for the action potentials to propagate thus increasing the total number of active neurons at any given time for any given stimulus. while this may be beneficial in some aspects, it demands increasingly high amounts of energy to bring the extra fibres excited to their resting state. this causes accumulation of metabolites in the inter-cellular space which effectively decreases the amount of nutrients available for the cells to metabolize. this, accompanied with a decrease in blood pressure associated with sleepiness which decreases the effective perfusion of neural tissue causes fatigue of the neurons.

    this leads to a vicious cycle terminating in sleep. while factors increasing the sympathetic activity and eventually increasing the blood pressure negate the above said effects and bring back the state of stable consciousness. so, if we provide a constant supply of energy and are able to keep the neural perfusion optimal, could we reach a state where sleep is no longer mandatory?

    assuming that the pruning in partial sleep is slower than the pruning in deep sleep, is it safe to say that less sleep will increase your intelligence by effectively increasing the number of synapses between different neurons (it actually decreases the amount of pruning)?

    the answer appears to be a no. given the vast number of connections possible and the vast number of connections that are formed, you wouldnt want a dominant thought about, say, a book you have read recently while driving your car on way to work! and if what i typed above is right, by giving inadequate sleep to the body, one is prolongating the course of the vicious cycle i talked about, and even if an eqilibrium is eventually reached, connecting different low resistance circuits in the brain doesnt seem to be a great idea (imagine urself trying hard to remember the answer to a question in an examination (high resistance pathway) but all you are able to think about is the movie you watched last year (low resistance pathway)).

    question arises what makes certain memories low resistance spontaneously while others are not?
    what makes you choose the high resistance pathways over the low resistance pathways?

    it is probably because this high resistance pathway does not leak into any low resistance pathway coz if that had happened, the low resistance pathway would have been favoured (here, by low and high resistance pathways, i mean the AMPA and NMDA receptor pathways on the post synaptic terminals).

    please share ur views.

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