Sleepless aliens may be living on planets with no days, nights, seasons
Technology
Aliens may need a different cycle to regulate alertness, appetite, and more
(Web Desk) - Sleepless aliens may be living on distant exoplanets with no daylight or seasons.
The Milky Way boasts between 100 billion and 400 billion stars. Of these, 70% are small, cool red dwarfs called M-dwarfs.
And they could hold the key to extraterrestrial lifeforms that parallel deep-sea and ground-dwelling creatures on Earth.
A 2013 study estimated that 41% of M-dwarf stars have a planet orbiting in their habitable zone, or the range of orbits with the right conditions for liquid water.
That means over 28 billion planets orbiting M-dwarfs could hold one of the keys to life - and that's not even considering other types of stars.
These planets are in close-in orbit, meaning they interact magnetically and tidally with their host stars.
An M-dwarf star tugs harder on the near side of a planet than its far side, and the resulting friction slows the planet over time until its spin and orbit are synchronized.
Most planets orbiting M-dwarfs are likely tidally locked. This is when one hemisphere always faces the sun while the other faces away, doused in darkness.
The Moon, for instance, is tidally locked to the Earth, which is why we only see the Moon's bright side.
Unlike our home planet, these rocky bodies have no days, no nights, and no seasons.
Most living things have circadian rhythms, natural processes that repeat every 24 hours. They can originate from the body or respond to changes in the environment.
In humans, nearly every tissue and organ has its own rhythms that are tuned to the cycle of day and night.
Circadian rhythm is most commonly associated with the regulation of drowsiness and alertness.
However, the 24-hour cycle also affects body temperature, appetite, the release of hormones, and more.
Without light changes, creatures on tidally locked planets won't have typical circadian rhythms. By extension, there may be no need for sleep.
While we can't know for certain, we can base theories on organisms that live in near or complete darkness on Earth.
Deep-sea creatures, for instance, boast biological rhythms synchronized to stimuli like temperature and tides rather than light.
Scientists have adapted climate models to simulate such an environment, including on Proxima Centauri b.
Proxima Centauri b is an exoplanet that orbits the closest known star to the Sun.
Its position within the star's habitable zone has made it a favorable candidate to host life.
Simulations have detected an interesting relationship between the dayside and nightside of planets orbiting M-dwarf stars.
The dayside is always bright, while the nightside is perpetually bathed in darkness.
The contrast seems to trigger gusts of wind and atmospheric waves like those that cause Earth's jet stream to bend.
