Tech Notes

Time: The Rhythm of Life

July 01, 2016

Why does time only move in one direction?

Flies with a mutant gene that disrupts their circadian rhythms do not live as long as flies that have no such mutation, researchers from Oregon Stare University have found.

Throwing off a fly's circadian rhythm brings about "accelerated neurodegeneration, loss of motor function and premature death," according to the research.

Flies are pretty close to humans, when it comes to DNA makeup. So a similar path of destruction may also unfold for us, once we lose our inner beat.

Researchers have long suspected that the loss circadian rhythms would disrupt body's vitals operations: The new research shows causation whereas previous studies showed only correlation between the two.

Circadian rhythms are the built-in biological clocks of a sort, ones made up of groups of dedicated cell networks. Most creatures have them. They are loosely based on 24 hours cycles of light and dark. Bodies use them to regulate many of their processes, such as sleep, fertility, feeding habits and DNA repair.

When the rhythm is interrupted, neurons start to oxidate. This molecular damage, in turn, can further erode the biological clock. Oxidation is a natural thing: The circadian system limits oxidative damage by establishing homeostasis.

In almost each cell of the human body is a tiny molecular clock, made up by a set of protein gears. These gears play a role in almost every biological function, such as curing body hunger and sleepiness, and even affecting cellular division and the aging process overall.

Traditionally, it was thought the body had a master clock to synchronize time with all the cell clocks, called a suprachiasmatic nucleus (SCN), which has about 20,000 neurons, and resides in the brain.

Cells in the retina relay a message to the SCN when they sense light. The light cues, in turn, affect the SCN cells' firing rate, or the rate at which neurons send off electrical messages to other brain cells. The SCN messages affects a wide range of other brain-controlled body functions, such as regulation for thirst.

It also thought some researchers that the SCN also gives out a substance, a set of peptides, that may help help synchronize other cells. Others think that it is not the SCN, but rather all the individual cells working together to produce a daily rhythm.

From the March 27 2012 audio issue of Science News