Horses, much like people, seem to get better quality sleep at night if they get plenty of fresh air, exercise and opportunities to socialize during the day. Of course, it also helps to have a comfortable place to lie down at night. That’s the upshot of a study from Germany that sought to determine how housing and management affect equine sleep patterns.

The importance of sleep to equine health is a relatively new area of inquiry, says Lorenz Gygax, PhD, of Humboldt University of Berlin. “Until a few years ago, horse owners took relatively little interest in the resting behavior of their animals. But recently attention has increased considerably,” he says. “Horse magazines now often cover the topic. Also chat groups have even formed by owners of horses with signs of sleep deprivation on social media channels.”

The study

Gygax and his team selected 10 young, healthy riding horses that received exercise five days a week. Because the deepest and most restorative stage of sleep— the rapid eye movement (REM) stage—can only be achieved when lying down, the researchers attached sensors to the horses’ front legs to monitor how often and how long they were recumbent.

For the two-month study period, the horses spent nights (from 5:00 p.m. to 7:30 a.m.) alone in box stalls. They spent the day in one of three arrangements: alone in a stall, outdoors in a paddock alone, or outdoors in a paddock with a familiar equine companion.

The study design allowed for the rotation of each horse through the different daytime arrangements in various sequences. By the end of the experiment, all the horses experienced each daytime arrangement on two separate occasions.

Daytime slumber

The researchers discovered that the horses laid down most often during the day when they were outdoors with a friend. At night, the horses laid down less frequently, but for longer periods of time. “Different materials on the ground may explain differences between the indoor box and the outdoor paddock. The increased space available or the open view in the paddock might have provided a sense of security,” the researchers observed.

What’s more, the study horses were slightly more likely to lie down on those nights that followed days spent outdoors with a friend. “The sense of security perceived throughout the day may have been carried over into the following night,” the researchers note. “This would mean that the horses felt more secure in the night following a day with a higher sense of security, lying for longer and potentially allowing a higher amount of REM sleep.”

Sleep aids

On average, the study horses laid down three hours per night, with the duration ranging from 1.5 hours to 5.5 hours. Although it’s not clear exactly how much REM sleep horses need, says Gygax, “as far as can be assessed, these amounts of recumbency should give sufficient opportunity for deep sleep.”

Gygax says a sense of security helps horses sleep better. “This would include a stable social environment with liked social partners and ideally a view of the surroundings. Furthermore, a large lying area with a suitable deformable (soft) substrate (litter, sand in the outdoor area) must be available.”

Reference: “Comparing lying behavior of young riding horses on days in an individual indoor box, on an outdoor paddock alone, or in pairs and in the following night,” Equine Veterinary Journal, January 2024