Summer is upon us, and like every year it has been accompanied by an increase in worried calls to veterinarians and stable owners. Their concern? Dead horses. With more people exploring the countryside, many witness horses laying motionless on their side. And we all know that horses can only sleep standing up, because when they lay down, their organs get squashed, right? Well, not entirely. While it is true that horses, especially when out in the open, tend to sleep standing up so they can escape predators faster, there is no evidence that laying on their side causes them any damage. In fact, horses will mainly sleep lying down when they feel safe, either in the company of other horses or in the confines of their stable. Having such safe spaces is important for the animals’ long-term health, as the REM phase of their sleep cycle can only happen when the horse can fully relax. The REM phase is key for many mammal’s health, including humans! Out in the wild, in a herd, horses sleep in shifts where some horses stay alert while others rest. So if you spot a horse lying down in a field, you can relax knowing it is simply doing the same.