Penguins Sleep and Wake Thousands of Times a Day

Sleeping chinstrap penguin on a rocky beach in Antarctica

Biological Strategy

Chinstrap penguin

AskNature Team

Regulate Cellular Processes

Cells are the basic building blocks of all living systems, so cellular processes dictate how physiological processes occur within those systems. Cells (whether entire unicellular organisms or parts of multicellular living systems) grow, metabolize nutrients (that is, chemically transform them), produce proteins and enzymes, replicate, and move. Cells as part of multicellular systems rarely act alone, instead having ways to signal to start and complete simple to quite complex interactions. How skin heals is a good example of the role of cellular processes. Blood cells called platelets release clotting factors to stop the bleeding; white blood cells rid the area of foreign materials and release molecules to coordinate healing; cells called fibroblasts start rebuilding using proteins called collagen; new blood vessels form; and skin cells called keratinocytes create the new surface.

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Maintain Homeostasis

When a living system is in homeostasis, it means that internal conditions are stable and relatively constant. For example, a human’s internal temperature is approximately 37 degrees Celsius (98.6 degrees Fahrenheit) unless there’s an illness. The human body maintains this temperature despite external ambient temperature. However, as with all physiological processes, maintaining homeostasis requires communication and coordination. So living systems have ways to detect changes from the norm, mechanisms to cause an adjustment, and negative feedback connections between the two. A desert lizard called the Gila monster offers a good example of maintaining homeostasis. The lizard goes from eating large meals to fasting for extended time periods. To maintain its blood sugar levels at a steady level, when food is scarce, its endocrine system releases a hormone that raises its blood sugar levels.

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Birds

Class Aves (“bird”): Eagles, hawks, sparrows, parrots

Birds are evolutionary engineering marvels. They are descended from dinosaurs, but are far from our idea of heavy, scaly reptiles. Of the specific adaptions that set them apart, most notable is flight—although some mammals can fly, birds take the prize for abundance in the skies. Many birds have hollow, lightweight skeletons and specially-designed wings to help them stay aloft. They also have feathers made of keratin that help them stay warm, attract mates, and improve navigation and aerodynamics in flight. In contrast to their dinosaur ancestors, they lack true teeth and have replaced them with specialized beaks and bills.

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Chinstrap penguins maintain near constant alertness by only sleeping for seconds at a time.

Introduction

Chinstrap penguins (Pygoscelis antarcticus), native to the harsh environment of King George Island, Antarctica, exhibit a remarkable biological strategy in their sleep patterns. These penguins face unique ecological challenges, particularly during incubation when they must guard their nests against predatory birds like the brown skua (Stercorarius antarcticus). To meet these demands, chinstrap penguins have developed an extraordinary in the way they sleep.

The Strategy

Chinstrap penguins employ a strategy of frequent, ultra-short bouts of sleep known as microsleeps. Unlike conventional prolonged sleep observed in many animals, the penguins utilize numerous bouts of slow-wave sleep (SWS) interspersed with brief awakenings. On average the microsleeps last a mere 4 seconds, but they add up to more than 11 hours total per day. Some naps rest one hemisphere of the brain at a time, others rest the whole brain at once.

Even during periods of incubation, when vigilance is crucial, these penguins manage to balance their need for sleep with their need to protect their offspring.

Surprisingly, penguins nesting at the colony’s edge, where predation risk is higher, actually achieve better sleep quality than those in the center. This may be due to increased aggression from other penguins in the colony and the increased stress that produces. Additionally, these birds adjust their sleep patterns based on factors, with improved sleep quality during the middle third of the day.

The Potential

The adaptation of frequent microsleeps in chinstrap penguins offers valuable insights for potential applications in human sleep management. This unique strategy may inspire innovations for individuals who require heightened vigilance during specific tasks or professions, such as healthcare workers, emergency responders, and military personnel. Understanding the restorative value of microsleeps could lead to optimized sleep schedules that enhance cognitive performance and safety.

Chinstrap penguins’ ability to thrive despite fragmented sleep patterns underscores the resilience of nature’s solutions. Humans can draw from this adaptation to better understand how to balance rest and alertness in demanding environments. It also emphasizes the importance of adaptability in the face of ecological challenges, providing valuable lessons for designing more sustainable and resilient systems across various fields.

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Last Updated December 7, 2023

References

“Microsleeps, the seconds-long interruptions of wakefulness by eye closure and sleep-related brain activity, are dangerous when driving and might be too short to provide the restorative functions of sleep. If microsleeps do fulfill sleep functions, then animals faced with a continuous need for vigilance might resort to this sleep strategy … The investment in microsleeps by successfully breeding penguins suggests that the benefits of sleep can accrue incrementally.”

Journal article

Nesting chinstrap penguins accrue large quantities of sleep through seconds-long microsleeps

Science | November 30, 2023 | P.-A. Libourel et al.

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