What is the pineal gland?

Your pineal gland, also called the pineal body or epiphysis cerebri, is a tiny gland in your brain that’s located beneath the back part of the corpus callosum. It’s a part of your endocrine system and secretes the hormone melatonin. Your pineal gland’s main job is to help control the circadian cycle of sleep and wakefulness by secreting melatonin.

The pineal gland is shaped like a tiny pinecone, which is how it got its name (“pine”-al gland). However, it is pronounced “pin-ee-uhl.”

The pineal gland is the least understood gland of the endocrine system, and it was the last part of the endocrine system to be discovered.

What is the endocrine system?

Your endocrine system is a network of several glands that create and secrete (release) hormones.

A gland is an organ that makes one or more substances, like hormones, digestive juices, sweat or tears. Endocrine glands release hormones directly into your bloodstream.

Hormones are chemicals that coordinate different functions in your body by carrying messages through your blood to your organs, skin, muscles and other tissues. These signals tell your body what to do and when to do it.

The following organs and glands make up your endocrine system:

What is melatonin?

Melatonin is a hormone that’s mainly produced by your pineal gland. The importance of pineal melatonin in humans is not clear, but many researchers believe it may help to synchronize circadian rhythms in different parts of your body.

Circadian rhythms are physical, mental and behavioral changes that follow a 24-hour cycle. These natural processes respond primarily to light and dark.

Your pineal gland releases the highest levels of melatonin when there’s darkness and decreases melatonin production when you’re exposed to light. In other words, you have low levels of melatonin in your blood during the daylight hours and peak levels of melatonin during the nighttime.

Because of this, melatonin has often been referred to as a “sleep hormone.” While melatonin is not essential for sleeping, you sleep better when you have the highest levels of melatonin in your body.

Melatonin also interacts with biologically female hormones. Research has shown that it helps in regulating menstrual cycles.

Melatonin can also protect against neurodegeneration, which is the progressive loss of function of neurons. Neurodegeneration is present in conditions such as Alzheimer’s disease and Parkinson’s disease.

FUNCTION

What does the pineal gland do?

The main function of your pineal gland is to receive information about the daily light-dark (day-night) cycle from the retinas in your eyes and then produce and release (secrete) melatonin accordingly — elevated levels at night (during dark hours) and low levels during the day (during light hours).

Can a person live without a pineal gland?

Yes, you can live without your pineal gland. However, your body may have a difficult time with sleeping patterns and other physiologic functions related to the circadian rhythm without a pineal gland due to a lack of melatonin.

In very rare cases, a person with a pineal tumor may need surgery to remove their pineal gland. This is known as a pinealectomy.

ANATOMY

Where is the pineal gland located?

Your pineal gland is located deep in the middle of your brain. It sits in a groove just above the thalamus, which is an area of your brain that coordinates a variety of functions related to your senses.

What is the pineal gland made of?

Your pineal gland consists of portions of neurons, neuroglial cells and specialized secreting cells called pinealocytes. The pinealocytes create melatonin and secrete (release) it directly into the cerebrospinal fluid, the fluid that flows in and around the hollow spaces of your brain and spinal cord, which then takes it into your bloodstream.

How big is the pineal gland?

Your pineal gland is a tiny, cone-shaped gland that’s only about 0.8 centimeters (cm) long. In adults, it weighs about 0.1 grams.

CONDITIONS AND DISORDERS

What conditions and disorders affect the pineal gland?

Your pineal gland’s function and ability to release melatonin can be affected by the following conditions and situations:

  • Pineal gland tumors.
  • Injuries that affect the pineal gland.
  • Pineal gland calcification.

Pineal gland tumors

Pineal gland tumors are very rare, and there are several different types of them. They’re more likely to affect children and adults younger than 40.

Pineal tumors aren’t always cancer, but they still cause problems as they grow because they press against other parts of your brain. They can also block the normal flow of cerebrospinal fluid, which is the fluid that surrounds and cushions your brain. This blockage raises the pressure inside your skull, which is dangerous and requires treatment.

Injuries that affect the pineal gland

Damage to your pineal gland can cause it to work improperly. Approximately 30% to 50% of people who experience a traumatic brain injury (TBI) have issues with at least one endocrine gland in their brain, which includes the pineal gland and pituitary gland.

A traumatic brain injury can happen when there is a blow to the head. The injury can be penetrating, like a gunshot wound, or a non-penetrating injury, like being struck in the head during a car accident. Concussions are the most common type of TBI.

Pineal gland calcification

Calcification of the pineal gland is quite common. In fact, it’s so common that healthcare providers often use a calcified pineal gland as a landmark on x-rays to help identify different structures of the brain. Calcification happens when calcium builds up in body tissue, causing the tissue to harden.

Your pineal gland tends to calcify as you age. While some calcification is normal, excessive calcification can prevent your pineal gland from functioning properly. Some studies have revealed that the degree of calcification of the pineal gland is higher in those affected by Alzheimer’s disease. There’s a loose link between pineal gland calcification and some migraine and cluster headaches.

More studies need to be done to determine the exact effects of pineal gland calcification.

What are the symptoms of pineal gland problems?

If you have a pineal gland tumor, which are rare, you may experience the following symptoms:

What are common tests to check the health of the pineal gland?

Healthcare providers can look at your pineal gland with imaging tests, such as an MRI (magnetic resonance imaging) or a CT (computed tomography) scan. Providers use these imaging tests to help determine if you have a pineal tumor or cyst.

Providers may also use X-rays to check for pineal gland calcification.

Your provider can also check your melatonin levels with a blood test.

How are pineal gland conditions treated?

Pineal gland tumors may be treated with one or more of the following therapies:

  • Surgery: Surgical removal of a pineal tumor is difficult due to its location in the middle of your brain. Because of this, it’s not a common treatment. In some cases, a surgeon might remove the entire pineal gland (pinealectomy).
  • Radiation therapy: Radiation therapy focuses strong beams of energy to destroy cancer cells and prevent them from growing.
  • Chemotherapy: Chemotherapy uses drugs to destroy cancer cells and prevent them from growing.

If you have a condition that causes your pineal gland to secrete less-than-normal levels of melatonin, your provider may have you take an over-the-counter melatonin supplement.

CARE

What can I do to keep my pineal gland healthy?

Researchers and scientists still don’t fully understand the pineal gland and melatonin and their functions. Because of this, there are no known ways to keep your pineal gland healthy.

FREQUENTLY ASKED QUESTIONS

Why is the pineal gland called the “third eye?”

Since the pineal gland was the last of the endocrine glands to be discovered — and scientists still aren’t fully sure of all of its functions — the pineal gland has long been a “mysterious” organ. The pineal gland was commonly called the “third eye” for many reasons, including its location deep in the center of the brain and its connection to light via the circadian rhythm and melatonin secretion. Many spiritual traditions believe it serves as a connection between the physical and spiritual worlds.

Chakras are prominent in certain forms of Hinduism and Tantric Buddhism. The third eye chakra is considered to be the sixth chakra in your body. It’s believed to be linked to perception, awareness and spiritual communication and linked to the pineal gland. While there’s no scientific evidence to support these claims, many forms of spirituality and cultures emphasize the importance of the third eye chakra and the pineal gland.