Can moon cycles affect horse behaviour?

We explore an age-old question that fascinates horse owners, astrologers and scientists alike: can the moon really influence how horses behave?

From restless nights in the stable to unexpected bursts of energy, many riders believe they see patterns linked to the lunar cycle. But is there any science behind these observations, or are we simply being fanciful when the moon is full?

Throughout history, the moon has been credited with affecting both animals and humans. Farmers across various cultures once timed breeding and planting to the lunar calendar, believing certain phases boosted fertility and growth.

When it comes to horses, stories abound of more excitable, spooky or unpredictable behaviour around a full moon. Though often dismissed as folklore, they are persistent enough to spark scientific interest.

In theory, there are a few ways the moon could influence animals, including horses.

Light levels

A full moon significantly increases night-time illumination, sometimes up to 200 times brighter than a moonless night. This can alter sleeping patterns and visibility for prey and predators. Horses, as prey animals, are instinctively alert to light and movement, so brighter nights could make them more vigilant, reactive or restless.

Circadian rhythms

Just as daylight affects melatonin and other hormones regulating sleep and activity, some studies suggest that moonlight and lunar cycles can subtly influence circadian rhythms in animals. While research in horses is limited, findings in other species, such as marine life and birds, show measurable hormonal and behavioural shifts linked to the moon’s phases.

Gravitational effects

Some people attribute behavioural changes to the moon’s gravitational pull, which causes tides. However, most scientists agree this is unlikely to affect land animals, as the forces on individual bodies are negligible.

Scientific evidence for lunar effects on horse behaviour is intriguing but inconclusive.

A study presented at the 2019 Equine Science Society Symposium examined veterinary data from several hundred horses and found a small but statistically significant increase in colic cases during full-moon periods. The reasons remain unclear, though it’s speculated that subtle changes in behaviour, such as altered feeding or stress patterns, may play a role.

Other equine studies have found no strong link between moon phases and injury rates, reproductive success or general behaviour. However, some veterinary professionals anecdotally report that horses can be more restless, reactive or difficult to settle during brighter lunar phases, especially in a yard environment where artificial lighting may already disrupt natural rhythms.

While moon cycles might coincide with specific changes, they’re rarely the only cause. If your horse seems particularly reactive and unsettled around a certain time, it’s worth considering more practical explanations.

• Dietary changes: Shifts in forage quality, feed or turnout routine can affect energy levels and behaviour.
• Pain or discomfort: Low-grade lameness, gastric ulcers or saddle fit issues can cause irritability or tension mistaken for moodiness.
• Seasonal transitions: Changes in daylight, temperature or coat growth can all influence metabolism and behaviour.
• Hormonal fluctuations: The reproductive cycle of mares may cause unpredictable behaviour unrelated to lunar patterns.
• Stable management factors: Turnout schedules, herd dynamics and even neighbouring animals can alter stress and sleep.

In other words, while the moon might play a subtle role, most behavioural shifts have more complex roots. Keeping detailed notes on feeding, exercise and environment can help identify whether lunar patterns are consistent or coincidental.

There’s no need to fear a full moon. It’s more important to understand your horse, their normal patterns, sensitivities and responses to change. Keeping an open mind but a practical outlook ensures you’re responding to what your horse truly needs, rather than what the moon may be doing.

If you notice your horse becoming tense or unpredictable during a full moon, five simple strategies can help keep things calm and consistent:

1. Stick to routine: Horses thrive on predictability. Avoid major changes to feeding, turnout or work schedules during stressful periods.
2. Provide turnout and movement: Access to grazing and regular exercise helps dissipate tension and reduce anxiety.
3. Check lighting and stabling: Make sure horses can rest properly. Too much artificial lighting at night can compound the effects of lunar brightness.
4. Support gut health: Since studies hint at a link between moon phases and colic, providing consistent forage and hydration is key.
5. Observe and record: Note any changes in behaviour, appetite or droppings across the lunar month. Over time, any patterns that do exist will become clear.

If your horse shows unexpected or worrying changes in behaviour or health, being insured means you can access the right veterinary care and support, whatever phase the moon is in.