Melatonin functions to regulate your sleep wake cycle, increasing production at night to help you get to sleep.
1 in 3 adults have insomnia worldwide and 1 in 10 have enough to be diagnosed with the condition, making the study of the "sleep hormone" melatonin incredibly important.
Melatonin, often referred to as the "sleep hormone," is a natural hormone produced by the pineal gland in the brain. It plays a crucial role in regulating our sleep-wake cycle and circadian rhythms. In this comprehensive guide, we will explore the various effects of melatonin on the human body, its relationship with sleep, and its potential health benefits.
Melatonin is a natural hormone primarily produced by the pineal gland, a tiny gland located in the brain. It belongs to the endocrine system and plays a crucial role in regulating circadian rhythms, which are physical, mental, and behavioral changes that follow a 24-hour cycle. While melatonin production is influenced by light and darkness, it can also be produced synthetically in a laboratory and sold as a dietary supplement.
The pineal gland secretes melatonin in response to the daily light-dark cycle. It releases the highest levels of melatonin during the nighttime and minimal amounts during the day. The secretion of melatonin is influenced by the retinas in our eyes, which detect information about the daily light-dark cycle. However, individuals with blindness may experience irregular melatonin cycles due to the inability to detect light.
Melatonin has often been referred to as the "sleep hormone" due to its impact on sleep. While it is not essential for sleeping, having higher levels of melatonin in the body can improve sleep quality. The pineal gland releases melatonin in response to darkness, signaling the body that it is time to sleep. However, it is important to note that other factors, such as caffeine or alcohol usage, medications, mood disorders, and environmental factors, also influence sleep quality.
Melatonin plays a critical role in regulating the sleep-wake cycle, which is governed by our circadian rhythms. These rhythms synchronize various physiological processes in our body, including sleep, based on the 24-hour light-dark cycle. The pineal gland's secretion of melatonin during the nighttime helps align our internal clock with the external environment. Disruptions to this cycle, such as shift work or circadian rhythm sleep disorders, can lead to sleep disturbances.
Several factors can affect melatonin production, including age, sex, and environmental factors. Melatonin levels vary throughout different stages of life, with newborn babies initially receiving melatonin from the placenta and later through breast milk. Melatonin levels increase as a child ages, reaching peak levels before puberty. After puberty, melatonin levels decline and stabilize until around age 40, followed by a gradual decline with aging.
In addition to its role in sleep, melatonin also interacts with biologically female hormones and helps regulate menstrual cycles. Research has shown that melatonin plays a part in maintaining normal menstruation patterns. Its influence on hormonal balance can contribute to reproductive health and overall well-being in individuals with menstrual disorders.
Melatonin has been associated with potential anti-aging properties. Studies have shown that individuals who undergo surgical removal of the pineal gland experience an accelerated aging process. This suggests that natural melatonin production may play a role in slowing down the aging process. However, further research is needed to fully understand the mechanisms behind melatonin's potential anti-aging effects.
Pineal melatonin has also been found to offer protection against neurodegeneration, a progressive loss of neuron function. Neurodegeneration is commonly observed in conditions such as Alzheimer's disease and Parkinson's disease. Studies have shown that individuals with higher levels of melatonin may have a reduced risk of developing these neurodegenerative disorders.
To assess melatonin levels, healthcare providers can perform blood tests, urine tests, or saliva tests. However, these tests are not commonly conducted unless there are specific indications. The results of these tests can provide insights into an individual's melatonin levels and help diagnose certain sleep disorders or circadian rhythm disturbances.
Melatonin levels vary based on age and sex. Newborn babies do not produce their own melatonin initially and receive it from the placenta and breast milk. Melatonin production starts around 2 to 3 months of age, and levels continue to increase throughout childhood until reaching peak levels before puberty. After puberty, melatonin levels decline gradually until they stabilize in the late teens.
Age-related decline in melatonin production occurs after the age of 40, with levels decreasing as individuals continue to age. In individuals over 90 years old, melatonin levels can be less than 20% of young adult levels. Various factors contribute to this decline, including calcification of the pineal gland and issues with light detection due to eye conditions such as cataracts.
It is important to note that melatonin levels within the normal range differ based on age and sex. Healthcare providers can interpret test results and determine if melatonin levels fall within the expected range for an individual's specific demographics.
There are two main conditions related to melatonin issues: hypomelatoninemia and hypermelatoninemia. Hypomelatoninemia refers to lower-than-normal levels of melatonin, while hypermelatoninemia refers to higher-than-normal levels of melatonin. These conditions can be associated with various health conditions and disruptions in sleep patterns.
Hypomelatoninemia occurs when individuals have lower-than-normal levels of melatonin, either during the nighttime peak or in total production. This condition is often seen in individuals with circadian rhythm sleep disorders, which are characterized by disruptions in the timing of sleep. Types of circadian rhythm sleep disorders include delayed sleep phase disorder, advanced sleep phase disorder, irregular sleep-wake rhythm, and non-24-hour sleep-wake syndrome. Hypomelatoninemia can contribute to sleep disturbances and may be caused by primary factors (affecting the pineal gland directly) or secondary factors (environmental factors or medications).
Hypermelatoninemia refers to higher-than-normal levels of melatonin, usually with extended durations into the morning. While naturally occurring hypermelatoninemia is rare, it can be caused by excessive consumption of melatonin supplements or melatonin-related sleep medications. Certain medical conditions, such as hypogonadotropic hypogonadism, anorexia nervosa, polycystic ovarian syndrome (PCOS), spontaneous hypothermia hyperhidrosis, or Rabson-Mendenhall syndrome, may also be associated with hypermelatoninemia.
Symptoms of hypermelatoninemia can include daytime sleepiness, low body temperature, dizziness, and decreased muscle tone.
Melatonin supplements are available as over-the-counter dietary supplements, but their use is not suitable for everyone. While studies have shown potential benefits of supplemental melatonin for specific sleep disorders, it is important to consult with a healthcare provider before considering melatonin supplementation. Additionally, the FDA does not regulate dietary supplements, which can lead to variations in product quality and inaccurate labeling of melatonin content.
In addition to its role in sleep, melatonin also interacts with biologically female hormones and helps regulate menstrual cycles. Research has shown that melatonin plays a part in maintaining normal menstruation patterns. Its influence on hormonal balance can contribute to reproductive health and overall well-being in individuals with menstrual disorders.
Melatonin supplements have shown potential benefits for individuals with specific sleep disorders, such as delayed sleep-wake phase disorder (DSWPD) and non-24-hour sleep-wake disorder. DSWPD is characterized by a delayed sleep-wake cycle, with individuals going to sleep and waking up significantly later than the typical sleep-wake cycle. Non-24-hour sleep-wake disorder is a condition in which an individual's internal clock is longer than 24 hours, resulting in a delayed sleep-wake cycle each day.
While melatonin supplements can be beneficial for certain individuals, it is crucial to consider various factors before deciding to take them. It is essential to consult with a healthcare provider to determine the appropriate dosage and timing of melatonin supplementation. Factors such as age, existing health conditions, medication interactions, and individual sleep patterns should be taken into account. It is also important to be aware of potential side effects and quality concerns associated with melatonin supplements.
Melatonin supplements are not officially FDA-approved for any specific purposes or conditions. The lack of FDA regulation for dietary supplements can lead to variations in product quality and inaccurate labeling of melatonin content. Studies have shown that the actual melatonin content in supplements can be significantly different from what is stated on the label, both in terms of being lower or higher than advertised. This discrepancy can lead to potential side effects or a lack of desired effects.
The safety of melatonin supplements during pregnancy and breastfeeding is not yet well-established. There is limited research available on the effects of melatonin supplements during these periods, and it is best to err on the side of caution. Individuals trying to become pregnant or currently pregnant should avoid melatonin supplements unless specifically directed by a healthcare provider. Similarly, individuals who are breastfeeding should refrain from using melatonin supplements due to the lack of safety data.