The pineal gland produces several hormones. One of these, melatonin, helps regulate the body’s internal clock, including the sleep-wake cycle. The pineal gland may also help regulate female hormone levels and contribute to cardiovascular health and mood stability.

The pineal gland is a small, pea-shaped gland in the brain. Experts note it plays a crucial role in the secretion of melatonin and other hormones.

If an underlying condition or injury impairs the pineal gland, it can lead to a hormone imbalance. This can impact several systems in your body.

For example, an impaired pineal gland can disrupt your sleep patterns. It also plays a vital role in the cardiovascular system, which means long-term disruption may lead to more serious health problems.

Read on to learn about the pineal gland, what it does, and what happens when it malfunctions.

The pineal gland is light-sensitive. When it gets dark out, your pineal gland releases melatonin into your body. This may make you start to feel sleepy. This is because melatonin plays a role in regulating your sleep patterns (circadian rhythms). At night, the influx of melatonin can help you feel tired, which helps you fall asleep.

The pineal gland releases melatonin when it gets dark out. It allows you to fall asleep at night rather than in the middle of the day.

Some conditions that can affect the pineal gland’s ability to produce melatonin include:

  • pineal tumors
  • injury to the gland
  • craniopharyngiomas
  • rare genetic disorders

Several other, more common conditions and environmental factors may affect your sleep. If you are unsure what is causing sleep issues, you may want to speak to a doctor to help determine if an underlying condition may be responsible for changes in your ability to sleep.

Some alternative medicine practitioners believe you can detox and activate your pineal gland to improve sleep and open your third eye. No scientific research supports these claims, though.

Melatonin supplements

You may want to talk with a doctor if you experience sleep disturbances. There may be an underlying cause. A doctor can help diagnose and treat any underlying condition you may have.

That said, many people who need help falling asleep turn to melatonin supplements. These supplements provide a small dose of melatonin to your body, which may help you fall asleep by making you feel tired.

The National Center for Complementary and Integrative Health (NCCIH) notes the following possible benefits of melatonin supplements:

  • jet lag or switching time zones
  • delayed sleep-wake phase disorder (DSWPD)
  • possible help with autistic or other neurodiverse children
  • anxiety before or after surgery

Melatonin supplement use increased from 1999 to 2018, according to a 2022 study. Researchers noted that most people took a dose of 5 milligrams(mg) or less. Due to the increase in use and potential therapeutic benefits, they recommend more long-term studies to determine the safety and effectiveness of the supplement.

The NCCIH also indicates more research is needed to assess the safety and effectiveness of melatonin supplements, particularly long-term studies. They note that it is:

  • safe for short-term use for most people
  • not likely effective in treating chronic insomnia

They also note that it may not be appropriate for all people. You should consider talking with a doctor before starting a supplement. Possible risk groups include:

  • people taking medications for chronic conditions
  • people over the age of 65
  • breastfeeding or chestfeeding people
  • pregnant people
  • those who have had an allergic reaction to melatonin supplements before

You should use caution when selecting melatonin supplements. The Food and Drug Administration (FDA) regulates it as a supplement, which means they do not need the same testing standards as medications on the market.

Also, a 2017 study shows that more than 71% of tested melatonin products did not contain the specified melatonin within a 10% margin. Researchers also found an additional 21% that contained serotonin.

No more recent studies explore the content, but the NCCIH still warns that supplements may not contain what they claim.

Melatonin supplements may cause the following side effects:

  • sleepiness and drowsiness
  • grogginess in the morning
  • intense, vivid dreams
  • slight increase in blood pressure
  • slight drop in body temperature
  • anxiety
  • confusion

If you are taking one of more of the following medications, melatonin may cause an interaction:

  • fluvoxamine (Luvox)
  • nifedipine (Adalat CC)
  • birth control pills
  • blood thinners, also known as anticoagulants
  • diabetes medications that lower blood sugar
  • immunosuppressants, which lower the activity of the immune system

Learn more about melatonin for sleep.

Melatonin may also play a role in protecting against heart-related conditions. A 2016 study suggests that melatonin may help protect against cardiovascular issues such as atherosclerosis and hypertension. However, more research needs to be done into the potential functions of melatonin.

Experts also note that melatonin receptors are located throughout the body, including areas of the cardiovascular system. It may help with processes such as:

  • blood pressure regulation
  • regulation of heart rate
  • vascular resistance

In a 2018 study, researchers noted that maintaining melatonin levels helps maintain several body functions. More specifically, they noted its possible melatonin helps delay and prevent age-related conditions in the cardiovascular system.

The menstrual cycle may influence the pineal gland and melatonin levels.

A 2020 study looking at melatonin levels and the menstrual cycle noted that a few older studies found rising melatonin levels during the late luteal phase, suggesting that it may influence sex hormones.

In their own work, the researchers found similar findings, but they also noted that melatonin levels are lower when a person transitions from premenopause to postmenopause.

While previous studies indicated that melatonin may influence the rise of progesterone, the current study found that progesterone likely influences the rise of melatonin. This may indicate that melatonin responds to the menstrual cycle rather than influences it.

Still, other experts note that it may play a role in sexual health and reproduction. They note that low melatonin levels are associated with delayed puberty and lower fertility, noting that people who live close to the arctic circle have lower pregnancy rates during periods of prolonged darkness in the winter.

The size of your pineal gland may indicate your risk for certain mood disorders.

In one slightly older study from 2015, researchers found that a lower pineal gland volume may increase your risk of developing schizophrenia and other mood disorders. Additional research is needed to better understand the connection.

Another study from 2019 found that people with major depressive disorder (MDD) had a higher chance of having a pineal gland cyst than the average population. They also noted a smaller gland volume but mentioned that this did not affect symptom severity. Still, they suggested that the pineal gland may play a role in depression.

Experts indicate that melatonin produced in the pineal gland may help with antitumor activity. It may work at the cellular level and help slow cancer progression.

They also note that night shift workers have a higher incidence rate of developing hormonal cancers. This is due to the disruption of melatonin levels at night.

However, if you do develop a pineal gland tumor, it may affect many other things in your body. This is because the pineal gland is located near many other important structures and interacts heavily with blood and other fluids.

Some early symptoms of a tumor include:

  • seizures
  • disruption in memory
  • headaches
  • nausea
  • damage in vision and other senses

Researchers still do not fully understand the pineal gland and melatonin. They do know melatonin plays a role in setting sleep patterns with day-night cycles, tumor or cancer prevention, and regulating the cardiovascular system.

Melatonin supplements may help manage sleep disorders, such as jet lag, and in helping you to fall asleep. You should speak to a doctor before taking melatonin or other supplements if you regularly take medication, have an underlying condition, are pregnant, or are breastfeeding or chestfeeding.

If you are looking for a better night’s sleep, several methods may help you improve your sleep quality. The Centers for Disease Control and Prevention (CDC) recommends you take the following steps to help improve your sleep quality:

  • go to sleep at or around the same time each night, including on weekends
  • leave electronic devices, including computers, tablets, cell phones, and TVs, out of the bedroom
  • keep the bedroom cool, dark, and free from as much noise as possible
  • avoid caffeine, alcohol, or heavy meals a few hours before bed
  • get regular exercise during the day, but avoid it close to bedtime

If you still have trouble, you may want to consider cognitive behavioral therapy. This involves seeing a certified therapist and getting some sleep assessments. They can help you better understand your blocks to get enough or good quality sleep.

Learn more about 8 natural sleep aids.

The following sections answer some frequently asked questions about the pineal gland.

Why is the pineal gland called the third eye?

People may refer to the pineal gland as the third eye because, like your eyes, it responds to light and darkness. The gland contains light-sensitive cells that secrete melatonin in response to changing light throughout the day. It is responsible for helping your circadian rhythm or your sleep-wake cycle.

What two functions does the pineal gland regulate?

The pineal gland’s primary function is to regulate the circadian rhythm, including feeling tired and wakefulness. It does this through the secretion of melatonin. It also may play a role in several systems, including the cardiovascular system and sexual hormones.