Why the overnight hours matter more than you think

We spend a lot of time perfecting the concentrate feeds and worrying about what happens in the day when we’re around the barn. For many of us, the ten or twelve hours in between, the overnight stretch, mostly look after themselves. However, new research suggests these nighttime hours deserve more attention, and that a few small, relatively affordable changes can make a real difference.

Horses run on a circadian rhythm, an internal cycle of roughly 24 hours set mainly by light. In horses, this clock is unusually sensitive to the light around them. Work from the equine chronobiologist Barbara Murphy and colleagues has shown that bright white and blue-rich light at night suppresses melatonin, the body’s signal that night has arrived, while dim red light barely touches it. Humans doing late or early chores around horses under red light has been shown to help horses stay calmer, rest better and eat more readily. The research suggests that even switching a white light on at 10pm for a late-night check disrupts the rhythm, so if switching to red light at night is an option, it’s genuinely a good one!

Appetite follows the clock, too. When Kentucky Equine Research tracked stabled horses overnight with chewing sensors, eating peaked in the early evening and eased through the night, with a rest phase in the early hours. They then began to eat with more gusto again around dawn. However, this is not a sign that horses can go without forage overnight. It simply shows that horses pace themselves while hay is available, eating, resting and returning through the night as they feel like it. A resting horse still produces stomach acid, so an empty net at night means a forced fast, not a natural one and this can be damaging to the stomach lining resulting in ulcers.

A few things that help:

• Keep forage trickling overnight. If your horse copes well with a hay net choose one with a hole size that their ration of hay lasts through the night.
• Mind the lights. Swap bright white for dim red on night checks where possible.
• Hold the routine. A predictable daily rhythm may matter as much as the clock itself.

This post draws on research from Kentucky Equine Research and on equine chronobiology work led by Barbara Murphy at University College Dublin.