All energy in the universe comes from light. On our planet, light comes from the sun and the earth’s core. Light itself has no mass, only momentum, but when it interacts with matter, it can be transformed:

E=mc2 (Mass Equivalence)

Einstein taught us that energy cannot be created nor destroyed, only transformed. When light slows down, mass (stored energy) is increased. As mass of an object decreases, light is liberated.

Life uses mass equivalence to control all its growth and metabolic processes in the body. We need to consume food to grow, and break food down to release energy to power life. If we breakdown too much of our mass, our bodies atrophy. If we cannot breakdown enough of our mass, we become obese and inflamed.

Light interacts with atoms. All matter is made of atoms, and atoms are made up of subatomic particles: electrons, protons and neutrons. Neutrons have the highest mass and electrons have the lowest mass. When light hits an atom, it only interacts with the electrons. When an electron absorbs light, it becomes excited and jumps up to a higher energy state (orbit) further from its nucleus.

Image result for excited state electron

Within 10^-8 seconds, the electron falls back down to its ground state closer to the nucleus while releasing its energy.

Living things absorb light during the day from the sun and the earth and emit that light at night. This energy flow is driven by the day/night cycle of the earth’s rotation which is 24 hours. This transition controls both sleep and wakefulness in all living things called the circadian rhythm.

Image result for suprachiasmatic nucleus

Upon sunrise, light travels through the eye where it is absorbed by photoreceptors that transform light into an electrical signal using electrons. The signal travels through the optic nerve to a region in the brain called the hypothalamus where it reaches the suprachiasmatic nucleus (SCN). The SCN is the master clock in the brain that acts as a timing mechanism to synchronize every biological process that occurs in the entire body within a 24 hour cycle. It communicates with every organ in the body to regulate:

  • Body temperature
  • Appetite
  • Metabolism
  • Mood
  • Digestion
  • Blood circulation
  • Reproduction
  • Sleep
  • Activity/Performance

All of these processes are driven by light through the eye. Every organ that is involved with regulating these processes has its own clock that runs slower than the SCN.

Sunlight drives the SCN during the day which stimulates wakefulness. At night when the sun has set, the SCN slows down which tells the organ clocks to also slow down so every system can regenerate during sleep by releasing the light energy absorbed during the day.

IMG sources:

Suprachiasmatic nucleus

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