Melanin and Melatonin

Uncovering the Top 10 Difference Between Melanin and Melatonin

Melanin and Melatonin

Melanin and Melatonin are distinct compounds with vital roles in the body. Melanin, a pigment, is produced by melanocytes and influences skin, hair, and eye color. It shields against UV radiation and comes in types: eumelanin and pheomelanin.

Conversely, Melatonin, synthesized in the pineal gland, regulates circadian rhythms, aiding sleep-wake cycles and mood. Its production is influenced by light exposure, with levels declining as we age. Melatonin supplements are also used. Despite their differing functions, both Melanin and Melatonin play crucial roles in well-being.

 Importance of Melanin and Melatonin

Melanin and Melatonin are essential compounds with distinct roles in the body. Melanin, a pigment, contributes to the determination of skin, hair, and eye color. It provides protection against the harmful effects of ultraviolet (UV) radiation from the sun.

Melatonin plays a crucial role in regulating the sleep-wake cycle and maintaining the body’s circadian rhythm. It helps synchronize biological processes with the natural day-night cycle.

While Melanin influences physical appearance and UV protection, Melatonin ensures proper sleep patterns andwell-being by promoting restful sleep and supporting mood regulation.

Definition of Melanin

Melanin is a biologically significant pigment found in various living organisms, including humans. It is responsible for the coloration of several tissues, including the skin, hair, eyes, and even some internal structures. Melanin is produced through a complex biochemical process involving specialized cells called melanocytes. These cells synthesize and deposit melanin in nearby tissues.

The primary function of melanin is to provide protection against the harmful effects of ultraviolet (UV) radiation from the sun. When skin is exposed to UV radiation, melanocytes produce more melanin, leading to tanning as a defensive response.

This increased melanin production helps absorb and dissipate UV energy, reducing the potential damage to skin cells’ DNA and lowering the risk of sunburn and skin cancer.

Melanin and Melatonin
Figure 01: Melanin and Melatonin

Melanin exists in different types, most notably eumelanin and pheomelanin. Eumelanin imparts dark colors, such as brown or black, to skin, hair, and eyes. Pheomelanin, on the other hand, contributes to lighter shades, often seen in people with red or blonde hair.

Beyond its role in pigmentation and UV protection, melanin has also been implicated in other biological functions, such as regulating body temperature, immune response, and even influencing neural and hormonal activities. Ongoing research continues to uncover the multifaceted nature of melanin and its potential impact on various aspects of human health and biology.

Definition of Melatonin

Melatonin is a hormone of crucial significance, primarily produced by the pineal gland located within the brain. This hormone serves as a key regulator of the body’s internal clock, known as the circadian rhythm. The circadian rhythm governs the natural patterns of sleep and wakefulness, coordinating these cycles with the daily progression from light to darkness.

Melanin and Melatonin
Figure 02: Melanin and Melatonin

Melatonin production is stimulated by darkness and inhibited by light, making it a central player in the sleep-wake cycle. As the evening sets in and light levels diminish, the pineal gland ramps up melatonin synthesis, signaling to the body that it’s time to wind down and prepare for sleep.

Conversely, exposure to bright light, particularly blue light emitted by screens and electronic devices, can suppress melatonin production, potentially disrupting sleep patterns.

Beyond its role in sleep regulation, melatonin has been implicated in other physiological processes. It may have an impact on mood regulation, immune function, and even antioxidant activities. Due to its influence on sleep, melatonin supplements are sometimes used to mitigate sleep-related issues, such as insomnia or jet lag.

Melatonin’s intricate involvement in the body’s daily rhythms underscores its significance in maintaining health and well-being. Researchers continue to explore its multifaceted effects and potential therapeutic applications in various domains beyond sleep regulation.

Chemical Composition of Melanin


Melanin composed of various units, including:

  • Dihydroxyindole (DHI)
  • Dihydroxyindole-2-carboxylic acid (DHICA)
  • Eumelanin: This type of melanin includes both DHI and DHICA units and is responsible for dark brown and black pigmentation.
  • Pheomelanin: This type contains sulfur-containing amino acids like cysteine and results in lighter pigmentation, such as red and blonde hair.

Chemical Composition of Melanin


Melatonin is a simple molecule derived from the amino acid tryptophan.

Its chemical structure includes:

  • Tryptophan: An essential amino acid that serves as the precursor for melatonin synthesis.
  • Serotonin: An intermediate compound derived from tryptophan, converted into N-acetylserotonin.
  • N-Acetylserotonin: Formed from serotonin and is then enzymatically converted into melatonin.

Differences between Melanin and Melatonin

Melanin and Melatonin are distinct compounds with different functions and characteristics:

  1. Function and Role:
    • Melanin: Melanin is a pigment responsible for determining the color of skin, hair, eyes, and other tissues. It offers protection against UV radiation and helps prevent damage caused by sun exposure.
    • Melatonin: Melatonin is a hormone that regulates the sleep-wake cycle and circadian rhythm. It helps control when we feel sleepy and when we are awake, aiding in the synchronization of biological processes with day-night cycles.
  2. Production Site:
    • Melanin: Melanin is produced by specialized cells called melanocytes, primarily located in the skin and hair follicles.
    • Melatonin: Melatonin is synthesized by the pineal gland, a small gland in the brain.
  3. Function in the Body:
    • Melanin: Melanin’s primary function is related to pigmentation and protection against UV radiation. It contributes to physical appearance and sunburn protection.
    • Melatonin: Melatonin primarily regulates sleep patterns, helping to initiate and maintain sleep at appropriate times. It also has potential roles in mood regulation and immune function.
  4. Light Sensitivity:
    • Melanin: Melanin doesn’t directly respond to light but can influence how the skin reacts to UV radiation.
    • Melatonin: Melatonin production is influenced by light exposure. Its synthesis increases in the evening when light levels decrease, promoting sleepiness.
  5. Types and Variations:
    • Melanin: There are different types of melanin, including eumelanin (dark pigments) and pheomelanin (lighter pigments). Individuals vary in the ratio and distribution of these pigments, leading to different skin and hair colors.
    • Melatonin: Melatonin levels vary throughout the day and night, with higher levels at night and lower levels during the day. It decreases with age, potentially contributing to changes in sleep patterns in older adults.

Comparison Chart between Melanin and Melatonin

Here’s a comparison chart highlighting the key differences between Melanin and Melatonin:

Aspect Melanin Melatonin
Definition Pigment responsible for coloration Hormone regulating sleep-wake cycles
Production Produced by melanocytes in skin, eyes Produced by the pineal gland in brain
Function Determines skin, hair, eye color Regulates circadian rhythm
UV Protection Absorbs and dissipates UV radiation Does not provide UV protection
Light Sensitivity Not directly influenced by light Produced in response to darkness
Types Eumelanin (dark) and pheomelanin (light) Singular hormone
Physiological Role Protects against UV damage, potential immune and neural roles Regulates sleep, mood, immune response
Variability Varies skin and hair color among individuals Levels fluctuate with day-night cycle
Production Factors Sun exposure, genetics Light exposure, darkness
Supplement Use Not used as a supplement Used to address sleep-related issues

Similarities – Melanin and Melatonin

While Melanin and Melatonin serve different functions in the body,

there are a few noteworthy similarities between the two compounds:

  • Biological Synthesis: Both Melanin and Melatonin are produced by specialized cells within the body. Melanin is synthesized by melanocytes, while Melatonin is produced by the pineal gland.
  • Natural Processes: Both compounds are integral to natural physiological processes. Melanin responds to UV radiation by darkening the skin to protect against sun damage, and Melatonin regulates sleep patterns and circadian rhythms to synchronize biological processes with day-night cycles.
  • Regulation by Light: Light plays a role in the regulation of both compounds. Melanin production can be influenced by sunlight, leading to tanning as a defense against UV radiation. Melatonin production is influenced by light exposure, with levels rising in response to darkness and declining in the presence of light.
  • Impact on Health: While their primary functions differ, both Melanin and Melatonin contribute to health. Melanin helps protect against UV-induced skin damage and potential skin cancers. Melatonin, by regulating sleep, supports restful sleep patterns, which are essential for  well-being.
  • Potential Antioxidant Properties: Some studies suggest that both Melanin and Melatonin possess antioxidant properties. Melanin may have a role in scavenging free radicals and protecting cells from oxidative stress. Melatonin’s antioxidant effects could help counteract oxidative damage in various tissues.
  • Complexity and Research: Both compounds have complexities that continue to be explored through ongoing research. While much is known about their primary functions, researchers are uncovering additional roles and potential benefits in areas beyond their initial understanding.


Melanin and Melatonin have distinct roles, but they share some commonalities. Both are produced by specialized cells, respond to light in different ways, contribute to health, and have potential antioxidant properties. These similarities underscore the complexity of our body’s biochemical processes and the interconnectedness of various compounds in maintaining well-being.

Reference Books list

  • “Melanin: Its Role in Human Photoprotection”
  • “The Melatonin Miracle: Nature’s Age-Reversing, Disease-Fighting, Sex-Enhancing Hormone”
  • “Melatonin: Nature’s Sleeping Pill”
  • “The Melatonin Hypothesis: Breast Cancer and Use of Electric Power”
  • Melatonin and the Biological Clock