Why people feel sleepy when they read?


Have you ever wondered why we feel sleepy when we read for a long time?

I found the answer when I was going through some of the Scientific facts in internet.

We usually feel sleepy when we study or read for a longer time. We conclude that we feel sleepy as the subject we are reading is boring or uninteresting.

But the actual reason is not that. We feel sleepy due to the posture in which we study. When we are studying for a long time continuously, lack of physical activity decreases our blood flow to muscles.

Due to this lactic acid accumulation takes place. Lactic acid is formed due to incomplete combustion in cells. Lactic acid is an agent which absorbs oxygen and it readily reacts with oxygenated blood thus reducing the flow of oxygenated blood to the brain.

Yawning also occurs due to reduction in the amount of oxygen in blood. So the amount of oxygenated blood to brain reduces and makes us feel sleepy.

To avoid this we have to take occasional breaks while studying,which involves some physical activity.


  • sriram balasubramanian

    explanation required...
    why lactic acid accumulation takes place? what relation it has with blood?
    incomplete combustion of "what" leads to formation of lactic acid?
    if lactic acid is the agent which absorb oxygen..then what about hemoglobin...

  • Unknown

    hello sriram
    I found the answer for lactic acid accumulation... and what happens due to accumulation..please visit this link..lots of stuffs involved..

  • Madman

    LOL i always study in lying down posture,if i study text books may my lactic acid secretion is hyperactive, this might be the case with the boring subjects. Ok what happens we watch TV for hours without moving lactic acid should be secreted right, may be pressing the remote lessens it a bit, i think hehehehehe.

  • Unknown

    @vemky: very funny.. i a not an expert in these areas... just found an interesting article and wrote about it..

  • pRiYaN...!

    thanx 4 posting such a wonderful article...because i feel sleepy whenever i see books...can you tell whats wrong wit me...


  • Unknown

    @priyan: nothing is wrong with you... because everyone feels sleepy when they re-open their books... so nothing strange about it..

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