MOSCOW, October 5 (RIA Novosti) - A study by scientists at the European Molecular Biology Laboratory in Heidelberg, Germany has found that melatonin, the ‘hormone of darkness’ which governs sleep patterns in humans, may also drive the nightly migration patterns of ocean plankton, science news site Science 2.0 reports.
The study, published in the scientific journal Cell, reveals that the sea creatures which are similar to those found in the Earth’s oceans hundreds of millions of years ago, have melatonin-generating capabilities which make them react to the day-night cycle similarly to mammals, including humans.
What’s remarkable about the findings, according to study co-author Detlev Arendt, is that the behavior of our ancient underwater ancestors “could have been the first form of sleeping.”
While studying the plankton known as Platynereis dumerilii, which are found in the Atlantic Ocean, the researchers sought to investigate “the effect of melatonin signaling outside vertebrates…in a zooplankton model.”
The research found that the plankton’s larvae migrate to the ocean surface and back during the day-night cycle. Arendt explained that the “cells in the brains” of these creatures which “sense light also run an internal clock and make melatonin at night.” This led them to the conclusion that “melatonin is the message these cells produce at night to regulate the activity of other neurons that ultimately drive day-night rhythmic behavior.”
The creatures’ cilia, or microscopic ‘flippers’ which beat regularly during the day, take long pauses during the night as melatonin is produced, prompting them to slowly sink into the ocean. At dawn, melatonin production stops and the flippers begin beating more quickly again, bringing the creatures closer to the ocean’s surface.
Virtually all animals have melatonin-producing mechanisms which regulate their sleep patterns. In humans, our eyes, sensing darkness approaching, send messages to the brain’s pineal gland, which secretes the hormone into the rest of the brain. As the eyes sense sunlight, we revert to a wakeful state. Breaking the day-night pattern results in physiological problems; we are fighting internal signals at the molecular level which are telling us to sleep.
In observing the plankton, Ardent says that it can help “elucidate the evolutionary origin of key functions of our brain. The fascinating picture emerges that human biology finds its roots in some deeply conserved, fundamental aspects of ocean ecology that have dominated life on Earth since ancient evolutionary times.”