Collective Dynamics of Sleep

Project Information

CO-SLEEP

Grant agreement ID: 101045788

DOI

10.3030/101045788

EC signature date 4 October 2022

Start date 1 January 2023

End date 31 December 2029

Funded under

• European Research Council (ERC)

Total cost

€ 2 912 102,00

EU contribution

€ 2 912 102,00

Coordinated by

UNIVERSITAT KONSTANZ
Germany

Periodic Reporting for period 1 - CO-SLEEP (Collective Dynamics of Sleep)

Reporting period: 2023-01-01 to 2025-06-30

Summary of the context and overall objectives of the project

Sleep is a biological imperative essential for maintaining health, cognition, social cohesion, and overall fitness. Yet, despite its importance, most research has focused on solitary individuals in controlled settings, overlooking the complex socio-ecological contexts in which many animals sleep. As a result, we have a limited understanding of how social environments influence the sleep of group-living species or how collective sleep patterns affect social structure and group functioning. This project shifts the study of sleep into a collective context, exploring how social processes shape sleep at individual, group, and population levels. By investigating the opportunities and constraints of sleeping in a group, we aim to uncover how animals navigate trade-offs between social needs, environmental pressures, and the biological requirement for sleep.

Focusing on wild baboons, we will examine how social relationships influence individual and collective sleep decisions, how the nocturnal environment constrains group-level sleep dynamics, and how sleep patterns contribute to group stability and coordination. We will develop an integrative framework combining advanced field methodologies with computational modeling to reveal interactions between sleep, sociality, and environment. To achieve these goals, we will validate minimally invasive methods for quantifying sleep in free-ranging animals and integrate GPS and accelerometry data from 30 wild baboon troops with overnight thermal videography, field experiments, and behavioral observations to construct dynamic models of collective sleep.

This project represents a major shift in the study of sleep, providing the first measurements of collective sleep behaviors in a socially and ecologically relevant context. By moving beyond individual-based approaches, it will transform our understanding of sleep as a collective phenomenon and illuminate how social and environmental factors shape sleep across levels of organization. It will also advance knowledge of the social and ecological trade-offs gregarious species, including humans, must navigate to meet the biological imperative of sleep and establish an interdisciplinary framework linking behavioral ecology, computational modeling, and the social sciences.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

The first two years of the CO-SLEEP project have been dedicated to building the necessary theoretical, research, and technological capacity to investigate the social dynamics of sleep in free-ranging baboons.

Validation study: The research team conducted experiments necessary for developing a novel method for detecting sleep and distinguishing REM from NREM sleep in wild baboons by combining accelerometers and thermal imaging. To support this approach, custom implantable data loggers were designed to record EEG and EMG data, representing a significant technological advancement essential for the validation study. These data will now be analyzed using deep learning models designed for sequence prediction to infer REM sleep. In conducting the validation study, the project integrated veterinary expertise with technology to create a novel and minimally invasive system for studying sleep in the wild. The team refined the surgical approach through iterative testing, ensuring minimal invasiveness while maintaining data quality. This validation study will enable the use of accelerometry and thermal videography as reliable tools for studying sleep by comparing them to the gold-standard in sleep research: polysomnography.

Capturing, collaring and monitoring of wild baboons: To investigate sleep and behavior across multiple groups while assessing the influence of ecological factors, large-scale monitoring is essential. Capturing and collaring wild primates at this scale is a major logistical challenge, requiring innovative methods to improve efficiency. To facilitate this effort, we have developed enhanced capture techniques, including improved trap designs for higher success rates, automatic locks to minimize escapes and enhance researcher safety, and remote trigger mechanisms to allow for the targeted capture of specific individuals. Currently, more than 100 animals are being tracked, with plans to expand monitoring efforts to 240 individuals in 2025 and to achieve full tracking of 30 groups by 2026.

Two publications connected to the project were published:
In "Sharing Sleeping Sites Disrupts Sleep but Catalyzes Social Tolerance and Coordination Between Groups" (Proceedings of the Royal Society B), we show that while sharing sleeping sites disrupts sleep, it also catalyzes social tolerance and coordinated movement between baboon groups. This highlights the influence of night-time social dynamics on daytime social relationships and demonstrates how sharing limited resources can drive intergroup tolerance.
In "The Sociality of Sleep in Animal Groups" (Trends in Ecology & Evolution), we argue that social interactions during sleep contribute significantly to animal groups' social dynamics. We propose a new framework using simultaneous monitoring of sleep in social groups, combined with time-series and social network analyses, to investigate how the social environment shapes and is shaped by sleep. This paper emphasizes the importance of considering the social environment in sleep research, as most studies treat sleep as an individual process, even though many animals sleep in groups.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

We are developing a novel minimally-invasive method to measure and stage sleep (i.e. differentiate REM from nREM sleep) using a combination of accelerometers, thermal videography, and polysomnography. The method would allow us to detect sleep and distinguishing REM from NREM sleep in wild animals. This approach will facilitate our ability to measure sleep in wild animals and will contribute to a better understanding of sleep's adaptive functions and evolutionary trade-offs. The technological and analytical tools we are developing will lead to a host of new studies focused on sleep in animals in the wild.

We have completed the development of RFID-controlled experimental feeders, which will be instrumental in testing hypotheses about the relationship between sleep and social cognition. Arrays of these networked feeders will make is possible for us to control resource access for individuals and groups at unprecedented social and spatial scales, and with unprecedented precision. The experiments that we will be able to conduct using this novel technology promises to allow entirely new types of field-based experiments, where decisions are made in ecologically relevant social contexts, rather than the highly unnatural, solitary decision-making typical of traditional laboratory experiments.

Both the validation of a non-invasive method for quantifying and staging sleep in free-ranging animals, and the experiments that will be possible using the RFID-controlled experimental feeders we have developed represent advances that go significantly beyond the state-of-the-art. Whether these lead to breakthroughs in our understanding or major advances in our field of study remains to be seen in the second phase of the project.

Olive baboons sleeping on tree.