Study reveals how Chinstrap penguins thrive on over 10,000 daily naps
Chinstrap penguins have perfected the art of napping for survival, taking over 10,000 microsleeps daily, each lasting just four seconds This remarkable adaptation ensures their survival in challenging environments
Chinstrap penguins have mastered the art of nodding off, taking over 10,000 four-second naps a day, according to a recent study. This daily strategy allows them to accumulate around 11 hours of sleep, challenging the idea that fragmented sleep is harmful to sleep quality, as seen in humans.
Inadequate sleep can lead to "microsleeps" or "micronaps" - brief periods of disrupted wakefulness characterized by eye closure and sleep-related brain activity. A study published in the journal Science on Thursday identified these occurrences in humans. However, nodding off in certain situations, such as while driving, can be dangerous, and it is uncertain whether these micronaps provide any of the advantages of regular sleep.
600 microsleeps an hour
In December 2019, researchers from France, South Korea and Germany conducted a study on 14 wild chinstrap penguins to explore the potential sleep functions of microsleeps and their feasibility as a sleeping method in ecological circumstances that demand constant vigilance. The penguins were incubating eggs in a colony on King George Island, Antarctica, which was under threat from a predatory bird, the brown skua.
While skuas are preying on penguin eggs during incubation, one penguin parent must constantly guard the eggs or chicks while their partner is away foraging. They also have to protect their nest from other penguins and find time to sleep. Researchers used remote EEG monitoring and non-invasive sensors to study their unique sleep patterns, recording brain activity, muscle tone, movement, position, temperature, as well as continuous video and direct observations.
The researchers observed that the penguins in the colony experienced over 600 instances of microsleep per hour. According to the study authors, the occurrence of "thousands of microsleeps lasting only 4 seconds" is unheard of, even among penguins.
In 1984, a small study discovered that little penguins kept in metabolic chambers showed a state known as "quiet wakefulness," similar to the microsleep of chinstrap penguins, but lasting an average of 42 seconds. In 1986, another study found that captive, nonbreeding emperor penguins also exhibited fragmented sleep referred to as "drowsiness," similar to the microsleep pattern of breeding chinstrap penguins, but they only spent up to 14% of the time in that state.
According to Paul-Antoine Libourel, a sleep ecophysiologist at the Neuroscience Research Centre of Lyon and coauthor of the study, 75% of sleep among chinstrap penguins consists of episodes lasting less than 10 seconds. He mentioned that while fragmented sleep is not uncommon in the animal kingdom, the ability of these penguins to sustain such extreme sleep fragmentation for days and hours, day and night, is what makes this finding particularly interesting.
He added that through these short bursts of sleep the penguins could "sleep and remain vigilant" while incubating.
Tourism in Antarctica is rapidly increasing, with thousands of visitors having a significant environmental impact on the delicate and already vulnerable ecosystems due to global warming.
Upon returning to shore, the researchers noted that the penguins maintained their original sleeping pattern despite having swapped partners for foraging at sea. However, they observed that the penguins slept for longer periods during their first hours back on land, suggesting that they needed to recover from sleep deprivation incurred during their active time at sea, particularly during diving activities.
Researchers also conducted comparisons on the sleep patterns of penguins nesting in the center of the colony versus those on the border, who are at higher risk of being targeted by predatory skuas and therefore need to stay more alert. Surprisingly, the penguins on the border slept more deeply and had longer and less frequent sleep episodes compared to those in the center of the colony, which was contrary to the researchers' initial expectations.
The researcher attributed the difficult sleeping environment in the colony center to the constant movement of penguins, including those passing by the nests of incubating penguins. This, along with aggression and other interactions, made it challenging for the penguins to rest. Although the restorative value of microsleeps was not directly measured, the researchers concluded that the chinstrap penguins' reliance on microsleeps and their successful breeding despite fragmented sleep patterns suggests that microsleeps may fulfill some of the restorative functions of sleep.
They concluded that other animals might also have "the flexibility to partition sleep into short or long bouts, depending on their ecological demands for vigilance."
An adaptation for survival
Libourel emphasized that the physiological mechanism enabling penguins to sleep in this manner remains unknown. He cautioned against emulating this sleep pattern due to the differing physiology between humans and chinstrap penguins, and the uncertainty surrounding the functionality of sleep for humans. Additionally, he highlighted that what may be detrimental for humans in terms of sleep patterns might actually be an adaptive mechanism for survival in other species.
Libourel emphasized the significant gap in our knowledge of the role of sleep and the impact of human interference and climate change on both sleep and animal life. He stressed the importance of studying sleep, considering it as a central aspect of animal behavior.
In a perspective published in Science, Christian Harding, a postdoctoral scholar at the University of California, San Diego, and Vladyslav Vyazovskiy, a professor of sleep physiology at the University of Oxford, highlighted that the study raises questions about the current understanding of sleep architecture regulation and the limitations of altering it before the benefits of sleep are compromised.
Climate change and human activity are increasingly impacting natural habitats, which in turn affects the sleep quantity and quality of wild animals. Researchers emphasized that conducting sleep studies in wild animals is crucial in order to observe their sleep patterns without human interference while the opportunity still exists.
CNN's Call to Earth editorial series is dedicated to covering the environmental issues that impact our planet, as well as the potential solutions. In collaboration with CNN, Rolex's Perpetual Planet initiative aims to increase awareness and education on critical sustainability issues and encourage proactive measures.
