Monthly Archives: May 2006

Light and Life – Part 3

This VERITAS was written on Tuesday, May 30, 2006
                      
Friends,

       This is part III of the VERITAS series in which we study the complex relationship between light and life.

       In the last VERITAS( MYSTERIES OF THE BRAIN : Part 14 , 19 May 2006) we saw that Adenosine and Melatonin are chemicals that make us tired and want to go to sleep and then help us sleep as long as there is darkness. Today we will understand Melatonin in detail and this will help us understand our body’s important relationship with darkness and night.

                   Swiftly walk over the western wave,
                   Spirit of Night!
                   Out of the misty eastern cave,
                   Where, all the long and lone daylight,
                   Thou wovest dreams of joy and fear,
                   Which make thee terrible and dear,-
                   Swift be thy flight
                                    – Shelly  ( “To the Night”)

       Melatonin is a harmone that promotes sleep. If this harmone is present in a greater quantity we feel more sleepy and if this harmone is
present in a lesser quantity then we feel less sleepy. This harmone is present in highest quantity in our bodies at night. This harmone is a part
of the system that regulates our circadian system( our internal system of light and darkness and therefore of time ).

       This harmone is present in nearly all creatures. Even simple creatures like algae have this chemical and this shows that nearly all creatures use Melatonin to regulate their body clocks. In some creatures Melatonin levels decides their skin colour which changes at night to prevent them from getting noticed by predators. Some animals use Melatonin levels to regulate their breeding patterns.

       In humans and other higher mammals Melatonin is produced in the pineal gland in the brain and the retina( in the eyes). This production is
controlled by the suprachiasmatic nucleaus in the hypothalmus ( called SCN). SCN is the primary controller of the circardian cycle. The SCN takes input about the presence or absence of light from the eyes and controls the production of Melatonin.

       AS humans we tend to hate the concept of darkness except when we sleep. We associate darkness with evil and fear. We associate light with hope and joy. In olden days when we did not have artificial light our bodies were exposed to longer periods of darkness. Now our brightly
illuminated homes and streets means that our exposure to darkness has become much lesser. We have banished darkness from our lives! Is that a good thing?!

       No, it is not! If our bodies are exposed to less darkness we have lesser Melatonin production in our bodies. And this does not just mean
that perhaps we are not sleeping as well as we were in the olden days. It means that our immune system is weaker, it means that we have more chances of cancer and it means that our resistance to stress is much less than our “unilluminated” ancestors!!!

       Research has shown that melatonin boosts the immune system. It does that by enhancing the production of T cells. Doctors administer
Melatonin sometimes to enhance the immune system of patients.

       Melatonin is a very powerful antioxidant. It reduces the damage to cells from the hydroxyl radical(OH) by neutralizing it. If the body has enough Melatonin then the damage to brain cells because of ageing is reduced. In tests on mice scientists found that mice with enough melatonin tend to live upto 20% longer. And this may be bacuse of their brains and immune systems being protected from these free radical attacks by the antioxidant properties of Melatonin.

       Research has shown that Melatonin prevents the damage to body cell DNA from carcinogens. Carcinogens are chemicals that damage the cell’s genetic code and may cause the cell to multiply endlessly like crazy – a condition known as cancer. For example benzene is a carcinogen and causes blood cancer. Melatonin prevents these carcinogens from damaging the cell DNA and thereby prevents cancer. Lack of enough Melatonin exposes you to more cancer risk. There is evidence of greater cancer incidence amoung people who work in light at night and sleep during the day. These people never get a chance to produce enough Melatonin. So Melatonin protects you from the cancer causing effects of chemicals and radiation.

       So we see that darkness of the night is not such a useless thing. It is not evil. It is not a sign of despair. It is very important so that we may produce enough Melatonin in our bodies. Thus it is not just important to sleep, it is very important that we get enough sleep and we get enough darkness at night!

          When from the clock’s last chime to the next chime
          Silence beats its drum
          And Space with gaunt grey eyes and her brother Time
          Wheeling and whispering come
          She with the mould of form and he with the loom of rhyme.

          Then twittering out in the night my thought birds flee,
          I am emptied of all my dreams:
          I only hear Earth turning, only see
          Ether’s long bankless streams,
          I only know I should drown if you laid not your hand on me

                                        -James Flecker (“Silence”)

Kanwar

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 Go, wondrous creature! mount where Science guides:
 Go, measure earth, weigh air, and state the tides:
 Instruct the planets in what orbs to run,
 Correct old time and regulate the Sun;
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Veritas by Kanwarpreet Grewal is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 United States License.

Mysteries of the Brain Part – 14 – SLEEP

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In this  VERITAS we will explore the structure of sleep. Sleep is not one big monolithic unit. It has various parts. And each of these parts has a specific purpose and specific character. Today we will explore these parts. We have seen in earlier VERITAS brain articles that human memory is
consolidated during sleep. In today’s VERITAS we will also find out the specific part of sleep that is associated with memory consolidation.

       We humans tend to look at sleep as a necessity but something that serves little purpose except giving the brain and the muscles some rest.
But the reality is different. During sleep the brain is very active. It is just not looking at the outside world. It is looking at itself and performing complex organizational tasks. The brain is not unconscious. It is in a state of altered conciousness. It is making sure that information acquired during the day is properly stored. It is improving the immune system. It is reducing harmful toxins from the various cells in the body. Sleep is a very interesting time and it is a very complex time. Indeed some researchers look at life from the opposite direction: That life is composed of various stages of sleep. And wakefulness is a stage of sleep where the body takes in nutrition and reproduces and prepares to enter into the other stages of sleep!

                Come, sleep, O sleep! the certain knot of peace,
                The baiting-place of wit, the balm of woe;
                The poor man’s wealth, the prisoner’s release,
                The impartial judge between the high and low.

                                                        ( Philip Sidney)

First let’s look at the triggers for falling asleep and waking up. Adenosine and Melatonin are chemicals in the brain that act as the sleep/awake triggers. Adenosine release happens when a person is awake. It keeps accumulating. The longer a person stays awake the more the level of
Adenosine in his body. Adenosine makes us sleepy. At certain levels of Adenosine the urge to sleep becomes overwhelming. Melatonin levels
increase in the darkness. It promotes sleep. As we sleep the levels of Adenosine  decrease. The levels of Melatonin decrease when sunlight enters the room and it is time to wake up. Caffiene reduces the effects of Adenosine and makes us feel less sleepy.

       When we fall asleep we go through various stages of sleep. The following are the stages of sleep. All these stages were discovered when
the electrical patterns of the brain activity were recorded using an EEG.

1) Stage I: This lasts about 5-10 minutes. The person is on a borderline between wakefulness and sleep. An EEG of the brain shows that there are  two types of waves produced in the brain at this time: the alpha wave  with a frequency of 8-13 cycles per second and a theta wave of 4-7
  cycles per second. The alpha wave is the awake wave- it is the sign of  a awake person. The theta wave is a signature of the first stage of
  sleep.

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2) Stage II: This is light sleep. The muscles become relaxed. The body temperature decreases. The response to outside sounds decreases. An EEG of the brain shows two features: sleep spindles and K complexes. A  sleep spindle is a sudden increases in wave frequency. A K-complex
  is a sudden increase in wave amplitude. This stage lasts a few minutes  and is also a light sleep stage.

3) Stage III and stage IV: This is deep sleep. These stages are marked by delta waves. Delta waves have the slowest frequency(1 to 4 cycles per
  second) and the highest amplitude. There is not much difference in stage III and IV. In stage III there are lesser delta waves. In stage IV more than half of the waves are delta waves. The rest are theta waves.

  The brain completes stage I through IV in about 90 minutes and then enters the most interesting stage:

4) REM stage: In this stage the brain electrical activity comes closest to  being awake. It shows alpha and beta waves. But the muscle tone
  dramatically decreases. The body is paralysed. The eyes start making fast movements in random directions. One part of the brain starts doing
  processing of information acquired during the day into memory but  another part of the brain starts making stories around that information.
  The body is kept paralysed because the brain does not want the body to act out these stories.  For details on dreaming and memory management
  see VERITAS: MYSTERIES OF THE BRAIN : Part 7, 1 May 2003.
  This stage lasts for about 10 minutes.

  During the night the body keeps repeating these stages one after the other with the exception of stage 1 that occurs only once. As the night
progresses the deep sl eep stages are reduced in length and the REM sleep length is increased. The last REM sleep stage( early morning) may last for an hour. That is why morning dreams are the most vivid and interesting.

       Small children spend a lot of time in REM sleep. They have a lot more information to consolidate.

    So we see that during REM sleep memories are formed. During non-REM sleep(stages 2 to 4) the immune system is strengthened and the body is rested.

       REM sleep is so important for the body that if a person deprived of sleep is given a chance to sleep for even an hour he will go directly into REM sleep without going  through the proper sleep stage sequence. So he may bypass stages 1 to 4 and jump to REM.

       We see that sleep is not a useless shutdown. It is a complex part of our life. A complex part that is still not fully understood. A complex
and enchanting world where we explore ourselves and our world without being tied to the chains of dull logic.

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               O soft embalmer of the still midnight!
               Shutting, with careful fingers and benign,
               Our gloom-pleas’d eyes, embower’d from the light,
               Enshaded in forgetfulness divine;
               O soothest Sleep! if so it please thee, close,
               In midst of this thine hymn, my willing eyes.
                                                       ( John Keats)

Kanwar

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=========================|
 Go, wondrous creature! mount where Science guides:
 Go, measure earth, weigh air, and state the tides:
 Instruct the planets in what orbs to run,
 Correct old time and regulate the Sun;
|======================================================|