UW-La Crosse Entomologist Barrett Klein is looking deep into the sleep patterns of bees to better understand what sleep might mean for all species — including humans. His research was published in July in the scientific journal PLOS ONE. It offers the first detailed spatial analysis of sleep ever conducted on an invertebrate society.
“Few have examined sleep in the context of a society,” explains Klein. “I am interested in how this mysterious and seemingly ubiquitous animal behavior operates and functions within a social group of organisms.”
Inside the honeybee nest, factors like temperature and position from resources may affect sleep, notes Klein. Worker bees, which are all female, are divided into castes — each caste performing a different task. He and his colleagues found bees of different worker castes slept in different areas of the nest relative to position of the brood and surrounding temperature. Older worker bees generally slept outside cells, closer to the perimeter of the nest, in colder regions, and away from uncapped brood. Younger worker bees generally slept inside cells and closer to the center of the nest, and spent more time asleep than awake when surrounded by uncapped brood.Also, the average surface temperature of sleeping foragers was lower than the surface temperature of their surroundings, offering a possible indicator of sleep for this caste. In the paper, Klein and his colleagues propose mechanisms that could generate sleep patterns for specific groups within the nest and discuss functional significance of these patterns.
Their work creates a foundation for investigating functional benefits of sleep that vary with task performed. It’s a topic particularly interesting in honey bees because the workers change tasks as they age, so individuals can be examined as they age and change tasks.
In addition, Klein’s research could lend insight into the best sleep patterns for social organisms faced with around-the-clock needs.
Klein, an assistant professor of biology at UW-L, has been studying honey bees since 2005. In addition to his recent publication, he published a paper in Proceedings of the National Academy of Sciences (PNAS). The paper examined a functional consequence of sleep loss in honey bees with respect to their ability to precisely communicate direction information when advertising the location of a food source to their siblings.