The pea-sized pineal gland resides deep in the center of the brain and produces the hormone melatonin. The most well known and understood function of melatonin is its role in synchronizing the daily wake and sleep cycle as well as other body biorhythms.
Many body organs and tissues possess melatonin receptors and respond in varied ways to the hormone. As such, a melatonin deficiency can lead to an array of possible health effects.
People with low melatonin levels often experience sleep disturbances, such as difficulty falling asleep or staying asleep. Melatonin levels typically increase after dark, peak during the night and fall as morning approaches. Because the hormone is particularly important for initiating sleep, people with low levels often experience difficulty falling asleep.
Seniors are especially vulnerable to melatonin-related insomnia as levels of the hormone tend to decline with age. Supplemental melatonin is frequently helpful for people who experience sleep difficulties related to a deficiency of the hormone.
People with chronic insomnia might benefit from the prescription medication ramelteon (Rozerem). This drug is a melatonin agonist, meaning it binds to certain melatonin receptors and mimics the action of the hormone in inducing sleep.
Increased Cardiovascular Disease Risk
Melatonin exerts a variety of effects on the heart and blood vessels and influences the levels of blood fats. Collectively, these effects help protect against cardiovascular diseases. Low melatonin levels frequently occur in people with high blood pressure, heart failure and coronary artery disease — fatty blockages in the arteries that supply blood to the heart.
The link between low melatonin and high blood pressure was examined in a study published in March 2010 in the Journal of Hypertension. The researchers found that among healthy young women without high blood pressure, those with the lowest baseline melatonin levels were most likely to develop hypertension during the 8-year follow-up period.
People with high levels of total blood cholesterol and bad cholesterol, or LDL, frequently exhibit low melatonin levels. These blood fat derangements increase the risk for developing coronary artery disease, the leading cause of heart attacks and heart failure. Because melatonin has anti-inflammatory and antioxidant properties, a low level of the hormone might also contribute to the development and growth of atherosclerotic plaques in the coronary arteries via these mechanisms.
Increased Cancer Risk
Melatonin deficiency has been linked to an increased risk for cancer, particularly breast, prostate and endometrial cancers. A February 2018 review article published in the journal Molecules reported that decreased melatonin levels might increase cancer risk by reducing the anticancer effects of the hormone. For example, all cancers exhibit damaged DNA, the genetic material within cells. Melatonin helps prevent DNA damage via its anti-inflammatory and antioxidant effects.
Other Possible Associations
Low melatonin levels might contribute to the development of several other medical conditions, although definitive associations based on human rather than animal research are lacking in some instances. Examples of medical conditions that might be more likely in people with a low melatonin levels include:
- Insulin resistance
- Type 2 diabetes
- Diabetes-related eye disease
- Recurrent miscarriage
- Alzheimer disease
- Parkinson disease
Additional resesearch is needed to clarify the potential link between low melatonin levels and these conditions.