Comparing lying behaviour of young riding horses on days in an individual indoor box, on an outdoor paddock alone, or in pairs and in the following night.
Authors: Helmerich Pia, Bachmann Iris, Gygax Lorenz
Journal: Equine veterinary journal
Summary
# Editorial Summary: Environmental Influences on Recumbency and REM Sleep in Young Horses REM sleep in horses is contingent on recumbency, and insufficient lying time can precipitate dangerous sleep deprivation events characterised by sudden collapse and associated injury risk. Helmerich and colleagues employed a cross-over design with ten young horses in training, fitted with 3D-accelerometers to automatically quantify lying bouts and duration across four conditions: stabled alone, paddocked alone, paddocked in pairs, and the subsequent night in individual boxes. Results demonstrated a marked circadian pattern—horses increased lying frequency during experimental days by approximately 21% and substantially extended lying duration at night (11-fold increase; p<0.001)—with a consistent numerical trend toward greater recumbency as environmental enrichment increased from confinement alone, through outdoor access alone, to paddock turnout with a companion, albeit without statistical significance due to high inter-individual variability. These findings have meaningful implications for yard management of young stock in training: whilst the protective effect of social and spatial enrichment on REM sleep acquisition did not reach conventional significance thresholds, the directional trend warrants consideration of turnout practices, particularly for horses displaying behavioural signs of sleep deprivation or those with injury risk from collapse. The authors appropriately acknowledge the study's limitation of small sample size and day-to-day variation, suggesting larger-scale investigations would clarify whether paddock access and peer companionship during the day genuinely support adequate nocturnal sleep architecture in young working horses.
Read the full abstract on PubMed
Practical Takeaways
- •Providing outdoor paddock access and social companionship during the day may improve horses' ability to achieve adequate REM sleep, reducing collapse risk from sleep deprivation
- •Young horses in training kept alone indoors show reduced lying behaviour; consider paddock turnout and compatible companions to support welfare and prevent sleep-related injuries
- •Monitor individual horses for variable responses to environmental changes, as large between-individual variation suggests some horses are more sensitive to housing conditions than others
Key Findings
- •Horses showed significantly higher numbers of lying bouts during daytime (p=0.05, 1.21× factor) compared to night
- •Lying duration was substantially longer at night (p<0.001, 11.25× factor) than during daytime
- •Open space and social pairing showed trends toward increased daytime lying bouts (1.08-1.17× factor) and duration (1.38-1.39× factor) though not statistically significant
- •Environmental conditions during the day influenced lying behaviour in subsequent nights, suggesting carryover effects on REM sleep opportunity