What are circadian rhythms?
Your circadian rhythm is your sleep-wake pattern over the course of a 24-hour day.
It helps control your daily schedule for sleep and wakefulness. Most living things have one. Circadian rhythm is influenced by light and dark, as well as other factors. Your brain receives signals based on your environment and activates certain hormones, alters your body temperature, and regulates your metabolism to keep you alert or draw you to sleep.
Some may experience disruptions to their circadian rhythm because of external factors or sleep disorders. Maintaining healthy habits can help you respond better to this natural rhythm of your body. https://www.healthline.com/health/healthy-sleep/circadian-rhythm#how-it-works
What are biological clocks?
Biological clocks are organisms’ natural timing devices, regulating the cycle of circadian rhythms. They’re composed of specific molecules (proteins) that interact with cells throughout the body.
Nearly every tissue and organ contains biological clocks. Researchers have identified similar genes in people, fruit flies, mice, plants, fungi, and several other organisms that make the clocks’ molecular components.
What is the master clock?
A master clock in the brain coordinates all the biological clocks in a living thing, keeping the clocks in sync. In vertebrate animals, including humans, the master clock is a group of about 20,000 nerve cells (neurons) that form a structure called the suprachiasmatic nucleus, or SCN. The SCN is in a part of the brain called the hypothalamus and receives direct input from the eyes.https://nigms.nih.gov/education/fact-sheets/Pages/Circadian-Rhythms.aspx
Have you ever had a bad case of jet lag? That horrible feeling when you get off a long haul flight and your body is telling you it’s time to go to sleep, but the outside world is telling you it’s time for breakfast? That’s the biological effects of your inner body clock, also known as your circadian clock.
Plants, fungi and even some bacteria have a circadian rhythm too. Although plants don’t tend to hop onto international flights, any living organism with a circadian clock has the potential to get jet lagged. This is more than a fun fact: we could use this information to make crops more productive and tackle food security.
The first reports of an inner body clock in plants stretch back to ancient Greece, when a ship’s captain studied the daily opening and closing of leaves on a tamarind tree.
The first systematic observations of plant circadian rhythms were conducted in the 1700s by the French scientist Jean-Jacques d’Ortous de Mairan who studied the rhythmic opening and closing of the leaves of Mimosa pudica (a plant in the pea family).
De Mairan noticed these cycles persisted even when the plant was in constant darkness. This demonstrated the leaf movements were not a response to changes in the lighting conditions, but were controlled by the plant itself. This is the definition of a circadian rhythm.
How plants tell the time
We now know these rhythms are controlled by a genetic network found inside each plant cell. About 20 genes control the circadian rhythm in plants. These genes switch each other on and off in a complicated circuit, generating a 24-hour rhythm.https://phys.org/news/2023-06-body-clocks-food-grown.html
https://phys.org/news/2023-09-captive-pandas-jet-lagged-body.html
https://phys.org/news/2023-08-complexity-bacterial-circadian-clocks.html
https://phys.org/news/2023-01-deepens-circadian-rhythms-mammalian-central.html
Although well studied in animals, plants, and bacteria, circadian rhythms all share an enigmatic property—the oscillation period is not significantly affected by temperature, even though the rate of most biochemical reactions changes exponentially with temperature. This clearly indicates that some sort of temperature-compensation mechanism is at play. Interestingly, some scientists have managed to replicate such temperature-invariant qualities in certain oscillating chemical reactions. However, these reactions are often troublesome and require extremely precise adjustments to the reacting chemicals.https://phys.org/news/2023-01-mimicking-enigmatic-property-circadian-rhythms.html
The research focused on fruit fly cryptochromes, key components of the circadian clocks of plants and animals, including humans. In flies and other insects, cryptochromes, activated by blue light, serve as the primary light sensors for setting circadian rhythms. The target of the cryptochrome photosensor, known as “Timeless” (TIM), is a large, complex protein that could not previously be imaged and thus its interactions with the cryptochrome are not well understood. https://phys.org/news/2023-04-circadian-rhythms.html
Life patterns help humans and other animals stay in sync with nature and in good form.
For several days after each November full moon, a wondrous spectacle occurs on the Great Barrier Reef in Australia: corals release into the water billions of eggs and sperm that unite to form free-floating larvae
These eventually settle, seeding new coral colonies.
Corals are not the only creatures to synchronize breeding by the light of the moon. Such rhythms are typically governed by circalunar clocks, a form of protein-controlled biological clock attuned to the 29.5-day cycle between new moons.
Synchronizations
Most multicellular organisms have, or are thought to have, some kind of inbuilt biological clock and many important processes including feeding and reproducing rely on accurate timings. The ability to stay “in sync” is key to survival.
“Understanding how the time-related interconnection of individuals within and across species works is critical for ecologically stable systems,” said Professor Kristin Tessmar-Raible, a neurobiologist at the University of Vienna in Austria.
Another, perhaps more familiar, form of biological clock—the circadian one—modulates the daily 24-hour sleep-wake cycle in response to environmental cues like light and temperature.
This complex system regulates everything from sleep and digestion to metabolism and mood. Researchers are shedding light on the environmental factors that may knock these biological rhythms out of sync.
But much about “chronobiology” remains unknown, including the mechanisms involved at a genetic and molecular level.
Earthwide implications
The findings may lead to new, effective recommendations for improving lifestyle patterns and protecting natural environments.
Meijer stressed the importance of how these things affect not just people but also all ecosystems.
“After billions of years of evolution, the light-dark cycle is good for animals,” she said. “Now, we’re throwing light over the Earth as if it’s harmless—and it isn’t.”
https://phys.org/news/2023-06-biological-rhythms-lot-animal-human.html
UNIVERSE 