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Night owls and morning glories

Posted: Saturday, April 07, 2001

Researchers beginning to look at why some horses perform better at certain times of the day

Some people are early birds. They hit the ground running early in the day, often before the sun rises; they think better, work more efficiently, and even exercise better in the morning. Others begin to perk up when the sun starts to go down. They stay up late to get projects done, like to take a sunset run, or get in a tennis game late in the day.

Certainly, different people function better at different times of the day, and the concept of daily rhythms is well accepted in the human medical field. But what about horses? Are there morning horses and night horses, too? Do some horses perform better early and some late?

Moreover, are there horses that sleep better in the mornings but are up at night, and others who are up early but prefer to sleep at night? And what, if anything, do these patterns of sleep and activity have to do with athletic performance?

Surprisingly little research has been conducted on the daily patterns and cycles of horses and "very little work done on horses in training," said Hilary M. Clayton, B.V.M.S., Ph. D., past president of the American Association for Equine Sports Medicine.

The very regimented routine of training and performance leaves few if any options for horses that may prefer to sleep late, so most horses are simply made to fit into the pattern of life at the track or training center.

Yet many trainers have had a horse or two in their barns that did not seem to be on the same schedule as everyone else. Some horses do not seem to sleep well at the track. They pace and fidget at night and consequently seem to be always tired in the morning. Other horses sleep well but are more alert and run better in the afternoons or evenings.

Some trainers feel that the differences in morning and evening temperatures may affect such horses or they look for other factors. Others simply feel that a small percentage of horses, like some people, are at their best at certain times of the day.

Circadian rhythms

These daily patterns or cycles are called rhythms. The best known is the circadian rhythm, which is a self-sustaining cycle of approximately 24 hours that is maintained even under conditions of constant light or darkness.

These rhythms involve behavioral events such as eating and sleeping, but they also involve cycles down to the cellular and endocrinological levels.

Corticosteriods, testosterone, glucose, and many other products in the body respond to cycles and tend to be elevated or depressed at different times in the day.

Though these rhythms persist under conditions of constant light or darkness, they can be influenced by many factors. Temperature, barometric pressure, drugs and hormones, and other environmental factors such as noise and activity can also affect them.

The most important influence is light. Light has been used in many ways to influence circadian rhythms in the horse. Increasing light is used to bring mares into earlier estrus at the beginning of breeding season, and decreased light is sometimes used to quiet horses.

Most horses adopt normal routines when placed in a stable environment. Research results vary somewhat on the total number of hours per day spent sleeping and when it occurs, but most horses seem to spend about four hours per day sleeping. Within that four-hour period, less than one hour is spent laying down flat on the ground in deep sleep.

Phases of sleep

Sleep is divided into three phases. The first is drowsiness, and horses are usually standing when in this phase. The animal's head droops and its eyes may close. This is a very light level of sleep and the animal is easily roused, especially by sound. Many horses will lean on fences or can be seen in this stage of sleep even when in crossties.

The second phase is slow-wave sleep. This occurs in the horse when either standing or when lying down on its chest. The horse droops its head and does not move. Though it may still be awakened, the horse requires more stimulation to rouse than from drowsiness.

The last sleep phase is REM or rapid eye movement sleep. This is the deep, restful sleep that is so important. During this stage of sleep, the horse is usually lying flat out and the muscles are relaxed and soft. Heart rate and respiration are lower but brain waves are similar to those of an awake animal.

Humans dream during REM sleep, but it is not known whether horses do as well. It was previously thought that horses could only enter REM sleep when they were lying flat out on the ground. This was observed to occur most commonly at night in pastured horses and to vary in stabled and trained horses depending on their training and turnout routines.

Recent studies of horses kept in standing confinement for use in PMU (pregnant mare urine) production, however, have shown that these horses adapt to their environmental constraints and learn how to enter REM sleep while standing up. Horses that did not lie down for six months experienced REM sleep while standing. These horses showed no ill effects or medical problems and did not appear tired.

Adapt to track life

From their experiences, most trainers would confirm that the vast majority of horses adapt well to a life of early-morning training and activity and stress at the barn and track. Most horses lie down in their stalls at night or in the afternoon and sleep for almost an hour. Occasionally a horse will lie down for four hours or more a day, but these individuals are rare.

It is thought that a well-run barn with clean, safe stalls and a stress-free environment will have proportionally more horses lying down in their stalls. The amount of clean bedding and the size of the stall have been linked to sleep patterns in stabled horses as well.

The amount of sleep needed for peak athletic performance has never been evaluated, and most trainers simply try to make their horses as comfortable as possible so that these horses adopt as near normal rhythms as possible.

Dressage and hunter-jumper barns report a slightly different pattern in that most horses sleep when they are brought into their stalls-mornings following night turnout and afternoons following morning work.

Some show trainers try to intentionally vary their training patterns, something that racing trainers cannot usually do. Dressage trainers will work a particular horse early, midday, and late on different days so that the horse does not establish a pattern.

This is thought to be advantageous because these disciplines have show times that can vary from early morning to noon to late afternoon and evening. A horse that is accustomed to working in the morning may be hopelessly flat and uninterested if required to show and compete at 8 o'clock in the evening.

Similarly, because these horses must sometimes compete in multiple classes throughout the day, some trainers do not let horses get in the habit of working only once and then relaxing. Periodically, they will work a horse twice in the same day.

Clearly, training and competition often go against the sleep and activity patterns that horses would like to establish and maintain. Most horses do not have a problem adjusting. Trainers often have innovative solutions for those few equine athletes that do not sleep well or seem out of rhythm.

Scott Lake, the Mid-Atlantic trainer who was nominated for a 2000 Eclipse Award as outstanding trainer, said he sometimes would seek out a quieter stable near the track to house a nervous or fidgety horse. "Sometimes a particular horse will just seem more comfortable with that situation," Lake said, "though most horses eventually settle into the track routine."

Music therapy

Drugs such as melatonin occasionally can be used to help adjust sleep and activity patterns in horses, and control of lighting and environment may also help some horses. One environmental factor is music, and radios in racing barns continue to be a controversial topic.

Katherine Houpt, V.M.D., Ph.D., professor of physiology and director of the Animal Behavior Clinic at Cornell University's College of Veterinary Medicine, has attempted to look at whether the type of music played may have some effect on horses.

Houpt observed ponies exposed to four types of music: rock, country, classical, and jazz. Though numerous studies have shown that music reduces stress in humans, this is one of the first such studies in horses. Her study showed country music to calm these ponies the most and jazz the least, but her final evaluation is more general and probably more realistic.

"Under normal barn conditions, the music and the type of music may affect the caretaker's job satisfaction, which in turn will affect his or her ability to handle the horses," Houpt concluded. In short, a happy caretaker means a happy horse. Companion animals-cats or goats, for instance-may also serve to settle some horses and bring about more normal sleep patterns.

Proper sleep is crucial for all athletes. A stable routine also is important for proper exercise and performance. Most adapt to rising early and working on a set schedule. Most likely, however, some individuals have different rhythms and seem better at different times in the day. Special care and attention may bring out the best in these specific horses.

So, if your horse seems to be active and ready to go early in the day, then you may have a true morning glory. But if your horse seems to be dragging until the afternoon approaches, then you may have a night owl on your hands. R

ecognizing that these different rhythms exist and being willing to pay individual attention to these special horses may help to get the best from a horse that just does not seem to fit into the normal routine.