Pineal Gland and Melatonin – Functions and Circadian Rhythm

Written by Drilon Beloshi | Last updated on August 4, 2023

The pineal gland is a small endocrine gland in the brain that is very important for our sleep-wake cycles and other basic bodily functions.

The pineal gland makes the hormone melatonin, which sets our body's 24-hour clock. Melatonin production goes up when it's dark, getting the body ready for sleep. When it's light, melatonin production goes down, getting the body ready to stay awake.

Melatonin makes you sleepy, but it also changes your defense system and your body's ability to fight free radicals

Read on to learn more about how melatonin and the pineal gland work together, and you might be able to improve your sleep and health.

The Pineal Gland: Anatomy and Function

Overview of location and function

location of the pineal gland

The pineal gland is a small gland in the form of a pinecone that sits in the epithalamus part of the brain. It varies in size in different animals. In humans, it is about 1cm in diameter. Despite its small size, the pineal gland exerts a surprisingly large degree of control over many physiological processes.

The pineal gland’s role in regulating circadian rhythms

Circadian rhythms are 24-hour biological cycles that control many bodily functions. They are mostly controlled by the pineal gland. When there isn't enough light, this endocrine gland lets out the hormone melatonin.

The pineal gland is a key part of the body's internal clock. It does this by responding to messages from light to control sleep, the production of hormones, and other important regular processes. [1]

Production and secretion of melatonin by pineal gland

Melatonin is a hormone that is generated and released by the pineal gland. It is made from the amino acid tryptophan by a series of enzyme processes.

When there is less light and less sensitivity to light, the pineal gland becomes more active and makes more melatonin. Therefore, melatonin levels are highest at night and slowly go down as morning comes.

Circadian rhythms, which include this secretion pattern, are essential for regulating sleep and wakefulness.

Melatonin and Circadian Rhythms

Understanding the concept of Circadian rhythms

circadian rhythm

Circadian rhythms, which happen naturally and internally on a 24-hour cycle, control how our bodies and minds work. The master biological clock in the brain controls these cycles based on information from the surroundings, mostly light and darkness.

The circadian rhythm regulates not just when we sleep and wake up but also our hormone levels, body temperature, metabolic rate, and cognitive performance.

By matching our actions to the natural rhythms of the body, we may be able to improve our daily performance, the quality of our sleep, and our health as a whole. [2]

The Role of Melatonin in synchronizing Circadian rhythms

Melatonin is a very important part of maintaining normal circadian rhythms. With the arrival of nightfall, the body receives a "time cue," signaling that sleep time is drawing near.

Melatonin levels rise in the evening and during the night, which makes it easier to fall asleep and stay asleep. Melatonin is helpful because it helps our circadian rhythms, or internal body clocks, match up with the outside world. This helps us sleep better and be healthier.

Disruption to Circadian Rhythms and the Impact on Melatonin Production

When circadian rhythms are disturbed, the way the body produces melatonin may change drastically. The circadian rhythm is the body's internal clock. Things like shift work, jet lag, bad sleeping habits, and being exposed to artificial light late at night can throw it off.

These modifications may decrease melatonin synthesis or shift the timing of its production, both of which contribute to difficulties falling asleep and maintaining a regular sleep-wake rhythm.

Circadian rhythms also control many bodily functions, such as hormone balance, immune function, and mood control. If melatonin isn't released enough, these functions can get messed up.

To protect natural melatonin production and get the most out of your circadian cycle, you need to stick to a normal sleep routine and limit your exposure to artificial light late at night.

Melatonin: The Sleep Hormone

Role of Melatonin in Sleep Regulation

woman sleeping

As soon as the sun goes down, the pineal gland lets out the sleep hormone melatonin. Melatonin helps people fall and remain asleep because it produces a feeling of peace and exhaustion.

It works with the circadian rhythm, which is the body's internal clock, to control when and how long a person sleeps. Melatonin supplements or increasing the body's natural ability to make it may help people better control when they go to sleep and when they wake up.

Exploring the link between melatonin and sleep quality

sick woman had a headache and touched her head on the bed.

Melatonin is closely linked to the quality of our sleep. Melatonin is helpful for sleep control since it makes you sleepy and less alert. It needs to be made in enough quantity for you to fall and stay asleep.

Poor sleep quality, difficulty falling asleep, and fatigue upon awakening are all signs of low melatonin levels or disturbances in production. Your health and the quality of your sleep may both improve if you take natural steps or take medications to raise your melatonin levels. [3]

The Pineal Gland and Light

Relationship between light exposure and melatonin production

back view of woman at home using headphones and tablet

The pineal gland's production of melatonin is very sensitive to the amount of available light. Light, particularly blue light, inhibits melatonin production, whereas darkness encourages its production. When its production stops, it makes it hard to sleep, especially in the evening and at night.

A decrease in light exposure sends a message to the pineal gland, telling it to make more melatonin. Melatonin makes you sleepy and helps control your sleep-wake cycle.

To keep melatonin levels fixed and help you sleep well, it is important to spend as little time in the light as possible, especially in the hours before bed.

Impact of Artificial Light on Melatonin Levels

Artificial light, especially that from electronics and energy-efficient lights, may interfere with the production of melatonin.

When people are exposed to artificial light late at night, it takes longer for them to fall asleep, which throws off their normal sleep-wake routine.

The blue light that electronic devices emit is particularly harmful because it reduces melatonin production.

Managing Light Exposure to Optimize Melatonin Levels

Light control is important for making melatonin work better and keeping regular sleep plans. Getting less artificial light in the evening, especially blue light, can help you make more melatonin.

This can be done by limiting computer time, turning down the lights, and wearing glasses that block blue light.

On the other hand, getting natural light during the day, especially in the morning, helps control melatonin and keeps the body's normal sleep-wake cycle going.

Controlling how much light you get may raise your melatonin levels, leading to better sleep and better health. [4]

Melatonin’s Health Benefits

Melatonin is a hormone that helps people sleep, but it also has many other health benefits. It is a powerful antioxidant that saves cells from oxidative stress by getting rid of harmful free radicals

People have said that this antioxidant property is good for heart health, immune system function, and maybe even preventing cancer.

Melatonin may help people with brain diseases like Alzheimer's and Parkinson's because it has anti-inflammatory qualities. Melatonin has also been shown to improve the function of the immune system, control the balance of hormones, and improve the health of the reproductive system.

Melatonin has a lot of different effects on health, which makes it a good subject for research that could improve people's health in general. [5]

Melatonin Supplements: Benefits and Considerations

Overview of Melatonin supplementation

Melatonin supplementation is when you take melatonin in pill form to treat sleep problems and improve the quality of your sleep. 

It is often used to help people with insomnia, jet lag, and other sleep problems. Melatonin is sold as an over-the-counter medication, and it comes in different doses and forms.

Melatonin pills might help, but you should only take them after talking to your doctor about the right amount and when to take them. It's also important to consider any side effects or drug conflicts that could happen.

Appropriate Dosage and Timing of Melatonin Supplements

woman's hand pours the medicine pills out of the bottle

There is no official dosage recommendation for melatonin supplements. An individual's optimal timing and dosage for taking melatonin supplements will vary from person to person.

Most people can take 0.5 to 5 milligrams as their first dose 30 minutes to an hour before bed with few or no side effects.

It has been shown that melatonin has the most effect on sleep-wake cycles when it is taken close to bedtime.

Melatonin is not a long-term solution, and it should only be taken for a short time under a doctor's guidance to lower the risk of abuse and other bad effects.

Frequently Asked Questions (FAQs)

What stimulates the pineal gland?

The pineal gland is most easily activated by prolonged periods of darkness or minimal exposure to light. When there isn't much light, the pineal gland works harder. 

This makes the hormone melatonin release, which controls when you sleep and wake up.

What happens when melatonin levels are high?

Melatonin tells your body that it's nighttime, which makes you feel tired and ready for bed. Melatonin helps control the sleep-wake cycle, so when you have more of it, it's easier to fall asleep and stay asleep.

Is it okay to take melatonin every night?

If you're having trouble sleeping, it's usually safe to take melatonin at night for a short time, like a few weeks. 

But you should consult a doctor before using it for a long time. Melatonin shouldn't be used continuously and without limits. 

What makes me sleep faster?

A more relaxing bedroom environment, a consistent bedtime routine, a lack of mental stimulation in the hours leading up to bed, and the use of relaxation techniques may all help you fall asleep more quickly. 

A dark room can help you increase your melatonin levels and in turn, help you sleep faster.

Who should not take melatonin?

Before using melatonin, you should check with your doctor if you are pregnant or breastfeeding, on any medications, or if you have ever had an adverse reaction to melatonin or a related substance. 

To make sure people are safe and comfortable, it's important to take into account the different circumstances of each person.

What are the bad side-effects of melatonin?

Melatonin may cause drowsiness, headaches, dizziness, nausea, and temporary alterations in blood pressure. There's also a chance that it could give you nightmares. 

When used for a long time or by people with certain health problems, the chance of hormone interaction goes up, so it's best to talk to an expert.


The pineal gland and the hormone melatonin control the body's circadian rhythms, sleep-wake cycles, and overall health. When it gets dark, the pineal gland releases melatonin, which makes us tired and helps our internal body clock keep time.

Melatonin supplements might help people who have trouble sleeping, but they should only be taken after seeing a doctor.

By limiting one's exposure to light, creating a peaceful bedroom, and sticking to a regular sleep schedule, one may increase one's melatonin levels and improve the quality of one's sleep. 

When we fully understand how melatonin and the pineal gland work together, we will be better able to appreciate good sleep and keep our circadian rhythms in check.


[1] C. (n.d.). Pineal Gland: What It Is, Function and Disorders. Cleveland Clinic. Retrieved from

[2] National Institute of General Medical Sciences. (n.d.). National Institute of General Medical Sciences (NIGMS).

[3] Effect of melatonin supplementation on sleep quality: a systematic review and meta-analysis of randomized controlled trials - PubMed. (2022, January 1). PubMed. Retrieved from

[4] Exposure to Room Light before Bedtime Suppresses Melatonin Onset and Shortens Melatonin Duration in Humans. PubMed Central (PMC). Retrieved from

[5] Melatonin: What You Need To Know. (n.d.). NCCIH.

About the author 

Dr Drilon Beloshi is a hardworking and passionate doctor who enjoys research, writing, and teaching. Conducted scientific research in the field of endocrinology.

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