English
Penguins in Antarctica have evolved an unusual sleeping strategy to manage the constant demands of parenting.
Guarding their chicks from predators and wayward penguins in a crowded colony requires round-the-clock attention.
During the breeding season, adult chinstrap penguins nod off thousands of times each day – but only for an average of four seconds at a time.
Yet according to new research these short microsleeps, totalling around 11 hours per day, appear to be enough to allow them to function for weeks at a time.
Won Young Lee, a researcher at the Korea Polar Research Institute is the co-author of new study published in the journal Science.
"The team visited Antarctica for the first time in 2014, and since then, we have been studying penguins. When we observed penguins in the wild, it didn’t seem like they were getting any sleep. Humans sleep seven to eight hours every night, but penguins seemed to have a series of short sleeps. Maybe it’s because predators nearby or other penguins made noises. We were curious whether penguins could get enough sleep in a day by getting a series of microsleeps."
Chinstrap penguins have a black line underneath their chin looking like the strap of a helmet, making them easy to identify.
For the first time, scientists have measured the sleeping behaviour of adult chinstrap penguins in the wild by attaching sensors that measure brain waves.
They collected data on 14 wild penguins over 11 days.
The idea for the study was hatched when Lee noticed breeding penguins frequently blinking their eyes open and shut during his long days of field observations.
"Past researchers had thought that microsleeps didn’t have any functions compared to normal periods of sleep and considered it something that occurs when a person is sleep deprived. But if you take a look at the result of the research, chinstrap penguins mostly depend on microsleeps. Although they are fragmented, if you put them all together, you can see that they spend half a day sleeping. Therefore, the study shows penguins get enough sleep through these fragmented periods of sleep."
The researchers did not collect data outside the breeding season, but they hypothesize that the penguins may sleep in longer intervals at other times of the year.
Researchers say they don’t know if the benefits of microsleep are the same as for long sleep.
It's unclear if chinstrap penguins in captivity share the same sleep patterns, but zookeeper Lindsay Ireland, says she's not surprised by the study's findings.
Ireland looks after Detroit Zoo's 81 penguins, including four chinstrap penguins, two males and two females.
"I'm not very surprised (about the results of the study), because we do see that similar behavior here. They're very active first thing in the morning when the lights come on and then you'll see them, after they eat, they'll kind of take a series of naps or they'll just be a little more sedentary in their location, whether it's on land or in the water."
Scientists have documented a few other animals with unusual sleeping patterns.
While flying, frigatebirds can sleep one half of their brain at a time, and northern elephant seals can sleep for 10 minutes at a time during deep dives, for example.
But penguin microsleeps appear to be a new extreme, researchers say.
"The smaller species of penguins like the chinstraps and the other ones that we have here will either sleep standing up with their head tucked underneath their flipper, or they'll actually lay down. We typically see them lay down when they're starting to take a longer nap. But mostly during the day, they’re short naps, they're standing up."
Daniel Paranhos Zitterbert who studies penguins at the Woods Hole Oceanographic Institution described microsleeping as an "amazing adaptation” to enable near constant vigilance.
Italian
I pinguini dell'Antartide hanno sviluppato un'insolita strategia del sonno per gestire le costanti necessità dell’essere genitori.
Proteggere i loro pulcini dai predatori e dai pinguini ribelli in una colonia affollata richiede un'attenzione continua.
Durante la stagione riproduttiva, gli adulti di pigoscelide antartico si appisolano migliaia di volte al giorno, ma solo per una media di quattro secondi alla volta.
Eppure, secondo una nuova ricerca, questi brevi microsonni, per un totale di circa 11 ore al giorno, sembrano essere sufficienti per consentire loro di funzionare per settimane.
Won Young Lee, ricercatore presso il Korea Polar Research Institute, è coautore del nuovo studio pubblicato sulla rivista Science.
"The team visited Antarctica for the first time in 2014, and since then, we have been studying penguins. When we observed penguins in the wild, it didn’t seem like they were getting any sleep. Humans sleep seven to eight hours every night, but penguins seemed to have a series of short sleeps. Maybe it’s because predators nearby or other penguins made noises. We were curious whether penguins could get enough sleep in a day by getting a series of microsleeps."
Gli esemplari di pigoscelide antartico hanno una linea nera sotto il mento che assomiglia al cinturino di un casco e li rende facilmente identificabili.
Per la prima volta, gli scienziati hanno misurato il comportamento del sonno degli esemplari adulti di pigoscelide antartico in natura, collegando dei sensori che misurano le onde cerebrali.
Hanno raccolto dati su 14 pinguini selvatici per 11 giorni.
L'idea dello studio è nata quando Lee ha notato che i pinguini riproduttori sbattevano spesso gli occhi durante le sue lunghe giornate di osservazione sul campo.
"Past researchers had thought that microsleeps didn’t have any functions compared to normal periods of sleep and considered it something that occurs when a person is sleep deprived. But if you take a look at the result of the research, chinstrap penguins mostly depend on microsleeps. Although they are fragmented, if you put them all together, you can see that they spend half a day sleeping. Therefore, the study shows penguins get enough sleep through these fragmented periods of sleep."
I ricercatori non hanno raccolto dati al di fuori della stagione riproduttiva, ma ipotizzano che i pinguini possano dormire in intervalli più lunghi in altri periodi dell'anno.
Affermano anche di non sapere se i benefici del microsonno siano gli stessi del sonno lungo.
Non è chiaro se gli esemplari di pigoscelide antartico in cattività condividano gli stessi schemi di sonno, ma la guardiana dello zoo Lindsay Ireland dice di non essere sorpresa dai risultati dello studio.
Ireland si occupa degli 81 pinguini dello zoo di Detroit, tra cui quattro pigoscelide antartico, due maschi e due femmine.
"I'm not very surprised (about the results of the study), because we do see that similar behavior here. They're very active first thing in the morning when the lights come on and then you'll see them, after they eat, they'll kind of take a series of naps or they'll just be a little more sedentary in their location, whether it's on land or in the water."
Gli scienziati hanno riportato la presenza di alcuni altri animali con schemi di sonno insoliti.
Mentre volano, le fregate possono far dormire metà del loro cervello alla volta, e gli elefanti marini possono dormire per 10 minuti alla volta durante le immersioni profonde, per esempio.
Ma i microsonni dei pinguini sembrano essere un nuovo estremo, secondo i ricercatori.
"The smaller species of penguins like the chinstraps and the other ones that we have here will either sleep standing up with their head tucked underneath their flipper, or they'll actually lay down. We typically see them lay down when they're starting to take a longer nap. But mostly during the day, they’re short naps, they're standing up."
Daniel Paranhos Zitterbert, che studia i pinguini presso il Woods Hole Oceanographic Institution, ha descritto il microsonno come un "adattamento sorprendente" che consente una vigilanza quasi costante.
Report by SBS News
