Researchers at the University of Helsinki have found that horses with more than 30 minutes of REM sleep nightly perform better in learning tasks than those with less. The study monitored 16 riding school horses over six weeks without disrupting their routines. Findings suggest REM sleep affects motivation and perseverance in horses.
A new study from the University of Helsinki reveals that horses achieving over 30 minutes of REM sleep each night show improved results in learning tests compared to those with shorter durations. REM sleep, which occurs only when horses lie down, was tracked in 16 riding school horses in their usual environment for six weeks. During this period, five rounds of 48-hour behavioral observations were conducted, including daytime learning assessments.
In the tests, horses first learned to touch an upturned bucket for a carrot treat. The task then advanced to include two buckets, with only one providing a reward, requiring seven correct touches before switching to the other bucket. All but one horse adapted to the changes, but those with reduced REM sleep persisted less on the task.
"Shorter REM sleep did not increase the number of mistakes, but had a particular effect on how long the horses worked on the task," said study author and veterinarian Mira Hämäläinen. "This suggests that REM sleep in horses is associated with motivation and perseverance."
Hämäläinen noted that simple tasks were learned quickly by all, but demanding ones highlighted the impact of limited REM sleep. Co-author Iina Brotherus, a doctoral researcher in equine sleep, stated the results provide a tool for evaluating horse learning and welfare, emphasizing sleep's role in wellbeing.
Laura Hänninen, another co-author, explained the study originated from work on learning tests and bedding but uncovered variations in rest among healthy horses. "Horses have this unique evolutionary adaptation skill where they can postpone their REM sleep for weeks, in some cases months, but that comes at a cost," she said. Even minor reductions affected performance, a pattern observed in humans and other species.
The research, conducted with the Finnish Equine Information Centre and SleepWell group members Tuire Kaimio and Henna-Kaisa Wigren, prompts further inquiries into sleep in horses with clinical issues or professional athletes. Hänninen wondered about differences in cognitive skills for competition horses adapting to travel and new environments.
Horse & Hound veterinarian Karen Coumbe commented that the findings align with evidence from other species, where reduced REM sleep links to mood issues, performance drops, and learning impairments. She stressed horses' sensitivity to handler cues and the need to prioritize their sleep, akin to humans.
