Can sleep behaviour be used as an indicator of stress in group-housed rats (Rattus norvegicus)?

We assessed the value of sleep behaviour as a novel measure of stress in group-housed animals. We observed, non-invasively, sleep behaviour in 144 group-housed rats, and related it to other physiological and physical indicators of stress and welfare. Sleep frequency and duration correlated negatively with adrenal weight, and positively with bodyweight gain, and final bodyweight. […]