Document Type

Dissertation

Degree Name

Master of Science (MSc)

Department

Psychology

Program Name/Specialization

Behavioural Neuroscience

Faculty/School

Faculty of Science

First Advisor

Nathan Insel

Advisor Role

Principal Investigator

Abstract

Sleep is essential for health, but leaves animals vulnerable to threats. Social living may mitigate this threat because vigilance can be distributed across group members. This predicts animals should sleep better with peers; however, often the opposite is found, possibly due to variations between species and social context. Degus (Octodon degus) are small, highly predated but also highly social rodents. Male and female degus show different behavioural patterns when encountering new peers, offering a unique window into how social sleep may depend on social relationships. We tested how the presence and familiarity of a peer influences sleep in degus. In Experiment 1, 48-hour video recordings were collected from cagemate and stranger pairs and scored manually for sleep. Males slept less with strangers than cagemates, while in females’ presence of a stranger reduced variance across animals. In Experiment 2, we repeated the procedure, adding a non-social condition and recordings of brain local field potentials, neck muscle electromyography, and movement acceleration—used to train a machine-learning (U-Net) classifier for sleep state. Adult females showed longer REM bouts with a familiar cagemate compared with when housed alone; however, there was no evidence of more REM or deeper, non-REM sleep. As with Experiment 1, variance of sleep was reduced when females were with strangers relative to cagemates—or to sleeping alone. Results offer some evidence that degus sleep better with a peer; meanwhile, reduced variance with strangers may offer insight into how female degus adapt to unrelated, unfamiliar individuals for group living.

Convocation Year

2026

Convocation Season

Fall

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Available for download on Tuesday, August 31, 2027

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