You Snooze, You Lose: Less Sleep Leads to More Offspring in Male Pectoral Sandpipers

ScienceDaily (Aug. 9, 2012) — During the breeding season, polygynous male pectoral sandpipers that sleep the least sire the most young. A team of researchers headed by Bart Kempenaers from the Max Planck Institute for Ornithology in Seewiesen has now discovered this extraordinary relationship. During three weeks of intense competition under the constant daylight of the Arctic summer, males actively court females and compete with other males.

Courtship flight: This male is trying to impress any watching female sandpipers with its feats of flight and inflated chest. (Credit: Wolfgang Forstmeier)

 

Using an innovative combination of tags that monitored movement, male-female interactions, and brain activity in conjunction with DNA paternity testing, the authors discovered that the most sleepless males were the most successful in producing young. As the first evidence for adaptive sleep loss, these results challenge the commonly held view that reduced performance is an evolutionarily inescapable outcome of sleep loss.

Sometimes it would be nice to have 24 hours available to finish the workload of the day. However, the drive for sleep inevitably compromises our performance or even causes us to fall asleep under dangerous situations, such as driving a car. Daily sleep is therefore thought to be essential for regenerating the brain and maintaining performance. This holds true both for humans and other animals. Researchers led by Bart Kempenaers from the Max Planck Institute for Ornithology in Seewiesen have now found that during the three-week mating period male pectoral sandpipers (Calidris melanotos) are active for up to 95% of the time. This is even more remarkable considering the fact that the birds have just arrived in their breeding area in Alaska, after migrating from their overwintering grounds in the southern hemisphere.

Pectoral sandpipers have a polygynous mating system where one male mates with several females. Because males do not engage in parental care, a male’s reproductive success is determined exclusively by his access to fertile females. However, gaining this access is not that easy for pectoral sandpipers: “Males have to constantly repel their rivals through male-male competition and simultaneously convince females with intensive courtship display,” says director Bart Kempenaers. Given that the sun never sets during the Arctic summer, males that can engage in this extreme competition 24/7 should be at an advantage.

Indeed, the researchers found that the most active males interacted most with females and sired the most offspring. Paternity was determined by collecting DNA from all males, all females, and all offspring in the study area. To measure activity patterns, the researchers attached transmitters to the feathers of all males and most of the females. These radiotelemetry based senders allowed the team to monitor whether the animal was moving or resting. Finally, recordings of brain and muscle activity confirmed that active birds were awake and that inactive birds were in fact sleeping.

The brain activity recordings also reveal variation in sleep intensity: “Males that slept the least had the deepest sleep,” says co-author Niels Rattenborg who conducts sleep research at Seewiesen. Although this suggests that the birds might compensate for sleep loss by sleeping deeper, the researchers found that even when this was taken into consideration, the birds were still experiencing a deficit in sleep.

Based on the team’s data on birds that returned to the study area across breeding seasons, this reproductive sleep loss apparently has no long-term adverse impact on survival. On the contrary, successful males returned to the breeding area more often when compared to males siring less offspring and were more likely to sire offspring in their second year. Does the study question the dominant view that the function of sleep is to regenerate the brain? The researchers do not wish to go that far, although the findings clearly show that under certain circumstances animals may be able to evolve the ability to forgo, or postpone, large amounts of sleep while maintaining high neurobehavioral performance.

Importantly, the finding that not every male does this, even when there are fertile females around, suggests that “Long sleeping males may lack genetic traits that enable short sleeping individuals to maintain high performance despite a lack of sleep,” argues Bart Kempenaers. The researchers believe that determining why only some males engage in this adaptive sleeplessness may provide insight into the evolution of this extreme behaviour, as well as the ongoing debate over the functions of sleep and its relationship to health and longevity in humans.


Story Source:

The above story is reprinted from materials provided byMax-Planck-Gesellschaft.


Journal Reference:

  1. John A. Lesku, Niels C. Rattenborg, Mihai Valcu, Alexei L. Vyssotski, Sylvia Kuhn, Franz Kuemmeth, Wolfgang Heidrich, and Bart Kempenaers. Adaptive Sleep Loss in Polygynous Pectoral SandpipersScience, 9 August 2012 DOI: 10.1126/science.1220939

Citation:

Max-Planck-Gesellschaft (2012, August 9). You snooze, you lose: Less sleep leads to more offspring in male pectoral sandpipers.ScienceDaily. Retrieved August 11, 2012, from http://www.sciencedaily.com/releases/2012/08/120809141625.htm

The Longer You’re Awake, the Slower You Get

ScienceDaily (July 27, 2012) — Anyone that has ever had trouble sleeping can attest to the difficulties at work the following day. Experts recommend eight hours of sleep per night for ideal health and productivity, but what if five to six hours of sleep is your norm? Is your work still negatively affected? A team of researchers at Brigham and Women’s Hospital (BWH) have discovered that regardless of how tired you perceive yourself to be, that lack of sleep can influence the way you perform certain tasks.


 

This finding is published in the July 26, 2012 online edition of The Journal of Vision.

“Our team decided to look at how sleep might affect complex visual search tasks, because they are common in safety-sensitive activities, such as air-traffic control, baggage screening, and monitoring power plant operations,” explained Jeanne F. Duffy, PhD, MBA, senior author on this study and associate neuroscientist at BWH. “These types of jobs involve processes that require repeated, quick memory encoding and retrieval of visual information, in combination with decision making about the information.”

Researchers collected and analyzed data from visual search tasks from 12 participants over a one month study. In the first week, all participants were scheduled to sleep 10-12 hours per night to make sure they were well-rested. For the following three weeks, the participants were scheduled to sleep the equivalent of 5.6 hours per night, and also had their sleep times scheduled on a 28-hour cycle, mirroring chronic jet lag. The research team gave the participants computer tests that involved visual search tasks and recorded how quickly the participants could find important information, and also how accurate they were in identifying it. The researchers report that the longer the participants were awake, the more slowly they identified the important information in the test. Additionally, during the biological night time, 12 a.m. -6 a.m., participants (who were unaware of the time throughout the study) also performed the tasks more slowly than they did during the daytime.

“This research provides valuable information for workers, and their employers, who perform these types of visual search tasks during the night shift, because they will do it much more slowly than when they are working during the day,” said Duffy. “The longer someone is awake, the more the ability to perform a task, in this case a visual search, is hindered, and this impact of being awake is even stronger at night.”

While the accuracy of the participants stayed the fairly constant, they were slower to identify the relevant information as the weeks went on. The self-ratings of sleepiness only got slightly worse during the second and third weeks on the study schedule, yet the data show that they were performing the visual search tasks significantly slower than in the first week. This finding suggests that someone’s perceptions of how tired they are do not always match their performance ability, explains Duffy.

This research was supported by NIH grant P01 AG09975 and was conducted in the BWH CCI, part of the Harvard Catalyst Clinical and Translational Science Center (UL1 RR025758-01), formerly a GCRC (M01RR02635). Development and implementation of the visual search task was supported in part by NIH grant R21 AT002571. JFD was supported in part by the BWHBRI Fund to Sustain Research Excellence; MM was supported by fellowships from the La-Roche and Novartis Foundations (Switzerland) and Jazz Pharmaceuticals (USA); SWC was supported in part by a fellowship from the Natural Sciences and Engineering Research Council of Canada.

 

Link:

http://www.brighamandwomens.org/about_bwh/publicaffairs/news/pressreleases/PressRelease.aspx?sub=0&PageID=1231

Journal Reference:

  1. Marc Pomplun,    Edward J. Silva,    Joseph M. Ronda,    Sean W. Cain,    Mirjam Y. Münch,    Charles A. Czeisler,    and Jeanne F. Duffy. The effects of circadian phase, time awake, and imposed sleep restriction on performing complex visual tasks: Evidence from comparative visual search. The Journal of Vision, July 26, 2012 DOI: 10.1167/12.7.14

Citation:

Brigham and Women’s Hospital (2012, July 27). The longer you’re awake, the slower you get. ScienceDaily. Retrieved July 29, 2012, from http://www.sciencedaily.com­ /releases/2012/07/120727111317.htm