Melatonin is a hormone produced in the pineal gland. Interestingly, the pineal gland is a tiny structure in the center of the brain that was described by René Descartes, a French philosopher, mathematician and scientist, as the “seat of the soul” in the early 17th century. He thought of the pineal gland as a place where all our thoughts are formed.

While the pineal gland has an important function, we have a much different understanding of its role today. Its main role is to be responsive to the light-dark cycles (length of the day and night periods). This information is used to determine when melatonin should be secreted.

Melatonin is released at night and plays a major role in regulation of the body’s circadian rhythms. Circadian rhythm refers to the physical, mental and behavioral patterns that occur over a 24 hour cycle in response to the light and dark periods. For example, melatonin influences are associated with sleepiness, maximum tiredness and with lowest levels of alertness and performance.

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While much attention has been focused on melatonin from the pineal gland and its role in sleep and the circadian rhythm, melatonin is also secreted by cells in other parts of the body including the salivary glands, esophagus, stomach lining and intestinal lining. The digestive tract has 100 times more melatonin than that found in blood and 400 times the levels present in the pineal gland. These sources of melatonin contribute to the blood levels especially during the day with release controlled by the periodic intake of food. Importantly, melatonin appears to have direct and indirect effects on the digestive tract, resulting in reduced secretion of stomach acid, promoting regeneration of the digestive lining and stimulation of the gut immune system.

Melatonin receptors (binding sites on cells) are found in many parts of the body including the brain, immune system, gonads, kidneys and cardiovascular system. The presence of receptors in these various locations underscores the importance of melatonin in the body and, at least partially, explains why melatonin has such a wide range of potential uses. Melatonin has antihypertensive properties and effects on regulation of heart rate. There is an important role in energy regulation and glucose metabolism. Antioxidant and anti-cancer properties have also been identified.

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Melatonin use in pets has focused on its potential benefits as an aid for sleep disorders, anxiety, cognitive dysfunction, adrenal abnormalities (Cushing’s disease), seizure disorders, and problems with nonallergic hair loss. As more is understood about the role of melatonin in the body, the list of health problems that will benefit from melatonin use will continue to grow.

It is important to note that melatonin levels in the pineal gland decrease as individuals age. In addition, there are numerous other factors that contribute to depletion or reductions in melatonin levels. These include certain herbicides, EMF (electromagnetic frequencies), electric light exposure (including TV and computers), stress, leaky gut syndrome, and certain drugs. Lack of exposure to sunlight can play a role in melatonin declines. This can be especially important during winter.

There are a variety of ways to help maintain or boost melatonin levels. These include using foods that are rich in tryptophan, such as certain meats, like beef, chicken, turkey and fish, peanuts and asparagus. Tryptophan is an essential component of melatonin production. Calcium is also essential, so foods like green leafy vegetables and sardines that increase calcium levels can be valuable. Vitamin D is critical for calcium absorption. Unfortunately, the majority of older pets have low vitamin D levels. Vitamin D is derived from the diet, not from exposure to sunlight, as it is with people.

Melatonin can be given as a supplement for health issues like anxiety, noise phobias, insomnia or night restlessness, cognitive dysfunction, digestive health, immune support and nonallergic hair loss. Before starting melatonin supplements, consult with your veterinarian. While melatonin is considered safe, avoid melatonin products that contain ingredients like xylitol, a sugar substitute that can be toxic to dogs. In addition, melatonin should also be avoided in pets that are diabetic, have autoimmune disorders or are receiving certain drugs like anticoagulants.

Make sure to discuss your interest in melatonin with your veterinarian before starting melatonin. Also, contact your veterinarian to discuss your pet health concern questions.

Ron Carsten, DVM, PhD, CVA, CCRT was one of the first veterinarians in Colorado to use the integrative approach, has lectured widely to veterinarians, and has been a pioneer in the therapeutic use of food concentrates to manage clinical problems. He is also the founder of Colorado Animal Rescue (CARE). In addition to his Doctor of Veterinary Medicine, he holds a PhD in Cell and Molecular Biology and is a Certified Veterinary Acupuncturist and Certified Canine Rehabilitation Therapist. He practices integrative veterinary medicine in Glenwood Springs.