In a two-choice experiment, cats (Felis domesticusi chose an active quail (Coturnix coturnix japonica) more often than a quail in tonic immobility (TI). In a second experiment, cats were individually presented with two active quail in an open field. Holding and biting by the cat, particularly about the neck, was necessary for inducing TI in a bird. Overall, the total time spent by a cat in stalking, attacking, and handling a bird was inversely related to the total time spent in TI by the bird. These results support the hypothesis that TI is a terminal defense mechanism elicited by predator contact. TI apparently eliminates the movement stimuli that sustain further attack.

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Introduction Feeling socially connected with others is essential for promoting and maintaining psychological health. Emerging research suggests that insufficient sleep may result in deleterious social outcomes such as greater reactivity to stressful social situations. However, little is known regarding how sleep may impact motivation to feel connected with others, and experiences of connectedness after positive social interactions. Methods Healthy participants (N = 56; 83.9% female, ages 18–30) were randomly assigned to one night of sleep restriction (SR, 4 h) or a night of typical sleep (TS, 8 h) in a controlled laboratory setting and verified with actigraphy. All participants did not have any known or suspected sleep or psychiatric disorders, were free of medical conditions and current medication use known to impact sleep and/or psychological functioning, and wore an actigraph for one week prior to the experimental night to ensure adequate sleep duration. Following the experimental night, participants reported on their motivation for social connectedness (e.g., “Right now, I would like to be close with friends, family, and significant others.”), and completed a task where they spent 5 minutes writing about a positive interpersonal event. After the task, participants reported on their feelings of interpersonal connectedness. Qualitative text analysis was conducted to extract emotional tone and number of social words used during the task. Results Compared to TS, participants undergoing SR were less motivated to feel connected with others [t(54) = -2.62, p = .01], and reported feeling less social connectedness after the task [t(53) = -2.06, p = .04]. Text analysis revealed no differences in positive or negative emotional tone, but participants in the SR group used less social words when describing their positive interpersonal event [F(1, 53) = 6.65, p = .01], even after adjusting for differences in total number of words used. Conclusion One night of sleep restriction reduces motivation to engage in social interactions, and also results in feeling less connected with others after reflecting on a positive social event. These findings add to a limited body of research on sleep and social experiences and provide further support for the negative psychological effects of sleep loss. Support (if any):