What is a Pineal Gland?

Erica Stratton

The pineal gland is a miniscule gland located in the human brain which secretes melatonin in response to light. It is located at the top of the spinal cord where it ends inside the brain, just above the cerebellum. It is about the size of a grain of rice. A great deal of blood flows through it, similar to the kidneys, so that the different chemicals it puts out can circulate through the body.

Traveling across time zones can confuse a person's circadian rhythms by disrupting the pineal gland and melatonin production.
Traveling across time zones can confuse a person's circadian rhythms by disrupting the pineal gland and melatonin production.

This gland is also referred to as the "third eye." The name does not connote psychic abilities. Instead, certain similarities to the light-sensing retinas of the human eye have led evolutionary scientists to theorize that it evolved from the same organ. In some animals, there is even a small hole in the skull through which light can reach their equivalent of the gland. In human beings, receptors in the eyes lead directly to the gland.

The pineal gland lies above the cerebellum.
The pineal gland lies above the cerebellum.

The role of the pineal gland in the human body is still being explored. It is thought to send out varying levels of hormones in response to seasonal changes in light, and in some animals, it regulates the related breeding urges. In humans, tumors in the pineal gland can sometimes cause a too-early onset of puberty.

The pineal gland secretes melatonin, which promotes sleep.
The pineal gland secretes melatonin, which promotes sleep.

Primarily, the pineal gland secretes melatonin, without which a person cannot sleep. The 24-hour sleep-wake cycle in humans is regulated by the gland producing more melatonin in response to light. In nocturnal animals, the process is reversed so that they come awake in response to darkness. For this reason, melatonin supplements are prescribed for people who have severe insomnia and for those with jet lag.

It is thought that many other disorders may be related to the gland's melatonin production. Those with bipolar disorder, depression, or obesity have achieved some relief after being treated with melatonin, but results are so far inconclusive. Disruptions in melatonin production may even cause effects as diverse as headaches, cancer, and gallbladder stones.

The pineal gland has somewhat of a romantic history in medicine. Early doctors and anatomists dissected it, but were unable to discover its purpose. Its similarity to an eye was debated. The philosopher Descartes pointed out it had to be of importance because of its singularity. His reasoning was that in the symmetrical human brain, all parts are doubled, but the gland had no counterpart. Therefore, he theorized that it was the seat of all original thoughts in the human mind.

Melatonin is a hormone produced by the pineal gland in response to light.
Melatonin is a hormone produced by the pineal gland in response to light.

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Magnesium is responsible for over 320 different biochemical reactions, enzyme and hormone production in the body, including the body’s own production of melatonin. When the body becomes magnesium deficient, the pineal gland in the brain is unable to produce and thus secrete this hormone any longer, which can negatively impact a person’s ability to switch off at night and fall asleep. Additionally, magnesium is the mineral that the body uses to relax the cells. When one is too wound-up or can’t relax, most people find it hard to nod off at night, and so people will take a magnesium supplement prior to bed for this reason.

The best magnesium supplement I have found by far is the Natural Calm product. I have not seen melatonin extracted from other animals, as is found in supplements, to work well on most people. Magnesium however, is the fourth most abundant mineral that the human body itself is made up of and is quite depleted in the current US diet. - Fifty Pence, Nutritionist


I wish it was that easy for me to get a good night's sleep. I have tried some melatonin supplements, but none of them seem to work for very long.

A few of them have worked for a couple weeks, and then after that they don't seem to have any effect.

I will have to check and see if the ones I was using were timed release or not. I will say, that some brands were better than others.

Sometimes I would feel really groggy the next day. It was nice to get some sleep, but I couldn't keep taking the supplement because I actually felt more tired through the day.

Has anybody else experienced this when taking melatonin supplements?


@SarahSon - You are right - our pineal glands do not make as much melatonin as we age. I have found it very helpful to take a natural melatonin supplement to help me sleep.

I have used several different over the counter supplements and have not found much of a difference in brands. What I have found that does work best is to use a time release supplement.

I think this does a much better job of helping me sleep for longer periods of time. When I took a supplement that was not a time release, I would sleep good for a few hours, but would be awake awhile before the alarm went off.

It makes so much difference if I can get a decent night's sleep. My life is hectic enough without dragging around and being grouchy because I can't sleep at night.


When I was younger, I would have never believed that I would have trouble sleeping. Now it seems like I rarely get a good night's sleep.

Even though I am exhausted, I can't seem to fall asleep. Other times I wake up several times during the night and can't get back to sleep.

A friend recommended that I try a melatonin supplement. The pineal gland must not secrete as much melatonin as we get older, because this seems to be a common problem for many people my age.

I have been thinking about trying an over the counter melatonin supplement. Has anyone been able to get a good nights sleep taking something like this?

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