Pineal gland function: Definition and circadian rhythm Health ConditionsHealth ConditionsAlzheimer's & DementiaAnxietyArthritisAsthma & AllergiesBreast CancerCancerCardiovascular HealthCOVID-19Dermatology & SkincareDiabetesEnvironment & SustainabilityExercise & FitnessEye HealthHeadache & MigraineHealth EquityHIV & AIDSHuman BiologyInflammatory Bowel DiseaseLeukemiaLGBTQIA+Men's HealthMental HealthMultiple Sclerosis (MS)NutritionParkinson's DiseasePsoriasisSexual HealthWomen's HealthDiscoverNewsLatest NewsOriginal SeriesMedical MythsHonest NutritionThrough My EyesNew Normal HealthPodcastsHow to understand chronic painWhat is behind vaccine hesitancy?The amazing story of hepatitis C, from discovery to cureNew directions in dementia researchCan psychedelics rewire a depressed, anxious brain?Why climate change matters for human healthToolsGeneral HealthDrugs A-ZHealth HubsHealth ToolsBMI Calculators and ChartsBlood Pressure Chart: Ranges and GuideBreast Cancer: Self-Examination GuideSleep CalculatorHealth ProductsAffordable Therapy OptionsBlood Pressure MonitorsDiabetic SuppliesFitness TrackersHome GymsGreen Cleaning ProductsHow to Shop for CBDQuizzesRA Myths vs FactsType 2 Diabetes: Managing Blood SugarAnkylosing Spondylitis Pain: Fact or FictionConnectAbout Medical News TodayWho We AreOur Editorial ProcessContent IntegrityConscious LanguageNewslettersSign UpFollow UsMedical News TodayHealth ConditionsDiscoverToolsConnectSubscribe What is the pineal gland Medically reviewed by William C Lloyd III, MD, FACS — By Zawn Villines — Updated on August 21, 2022The pineal gland is a small gland in the center of the brain. It secretes melatonin, which plays a role in the body’s internal clock. The primary function of the pineal gland is to control the cycle of waking and sleeping. It forms part of the endocrine system, which is the collection of hormone-secreting glands that regulate bodily processes. This article discusses the pineal gland and its functions. What is the pineal gland Share on PinterestREB Images/Getty ImagesThe brain has two hemispheres, connected by a network of fibers. The pineal gland is in the middle of the brain, in between the two hemispheres. The pineal gland mainly contains pinealocytes, which are cells that produce the hormone melatonin; and glial cells, which are a particular type of brain cells that support neurons. Neurons are cells that transmit information to other cells via electrical and chemical signals. Understanding circadian rhythms The pineal gland is key to the body’s internal clock because it regulates the body’s circadian rhythms. Circadian rhythms are the daily rhythms of the body, including signals that make someone feel tired, sleep, wake up, and feel alert around the same time each day. These rhythms recur naturally on a 24 hour cycle, even without light fluctuations. The pineal gland secretes melatonin, which is a hormone that helps regulate circadian rhythms. Melatonin is produced according to the amount of light a person is exposed to. The pineal gland releases greater amounts of melatonin when it is dark, which points to melatonin’s role in sleep. Some research, however, suggests that the link between melatonin and sleep might not be as simple as it seems. These researchers found that removing the pineal gland did not affect the activity levels of rats that had normal access to light and dark. They concluded that the function of the pineal gland may be more complicated than initially thought and that its role may vary widely between different animals. Other functions of the pineal gland The pineal gland has been linked to a range of other functions. These include: Bone metabolism Research on mice suggests that changes in the function of the pineal gland might affect bone metabolism. These findings may apply to humans as well — postmenopausal women are significantly more vulnerable to osteoporosis than other groups. Pineal gland function tends to decline with age. Researchers concluded that oral melatonin supplements might help increase bone mass, which could be used in the future to protect against postmenopausal osteoporosis. However, further research is necessary to assess the role of the pineal gland and bone metabolism in humans. Mental health Sleep deprivation can cause or worsen mental health conditions. Some mental health disorders may also make it more difficult to sleep. Access to daylight can also play a role in some mental health conditions. Seasonal affective disorder, for instance, is a form of depression that affects a person’s mood and tends to occur when light levels are low. This may be due to changes in melatonin secretion. A 2017 review, however, found no evidence that melatonin had any effect on mood disorders. Drug metabolism Some drugs, including both recreational and prescription drugs, appear to alter the function of the pineal gland and change melatonin secretion patterns. One older study using an animal model suggested that the pineal gland could play a significant role in addiction to cocaine and other psychostimulants. Aging As people age, the pineal gland tends to secrete less melatonin. It is unlikely that melatonin is the sole culprit for age-related changes, but reduced melatonin levels may help explain the aging process. Older adults tend to sleep less and may have trouble falling asleep. Changes in melatonin might explain this phenomenon. Pineal gland dysfunction The pineal gland may accumulate calcium deposits. These deposits are normal in healthy individuals, but excessive calcification can prevent the pineal gland from functioning properly. Because the pineal gland is closely associated with the hypothalamus, problems with the hypothalamus — including cancer, growths, or hormonal issues — can cause pineal gland dysfunction. Pineal gland tumors are rare but can also alter pineal function. The most prominent symptom of pineal gland dysfunction is a change in circadian rhythms. This might mean sleeping too much or too little, feeling active and restless in the middle of the night, or feeling sleepy at unusual times. Other symptoms of a problem with the pineal gland include:headache, nausea, vomiting, or tremordifficulty with sense of directionchanges in fertility, menstrual cycle, or ovulationosteoporosismental health issues, particularly seasonal symptoms More research may reveal additional pineal gland functions and determine how light and melatonin affect everyday health. Summary The pineal gland is a small gland in the center of the brain. It secretes the hormone melatonin and is primarily responsible for regulating patterns of sleep and waking. Calcium buildup and cancerous tumors may disrupt pineal gland function, but these are rare. Last medically reviewed on August 21, 2022EndocrinologyMental HealthNeurology / NeuroscienceSleep / Sleep Disorders / Insomnia 10 sourcescollapsedMedical News Today has strict sourcing guidelines and draws only from peer-reviewed studies, academic research institutions, and medical journals and associations. We avoid using tertiary references. We link primary sources — including studies, scientific references, and statistics — within each article and also list them in the resources section at the bottom of our articles. You can learn more about how we ensure our content is accurate and current by reading our editorial policy.Blackwelder, A., et al. (2021). Effect of inadequate sleep on frequent mental distress.https://www.cdc.gov/pcd/issues/2021/20_0573.htmDe Crescenzo, F., et al. (2017). Melatonin as a treatment for mood disorders: A systematic review [Abstract].https://www.ncbi.nlm.nih.gov/pubmed/28612993Sciacca, F. (2021).https://radiopaedia.org/articles/pineal-glandJehan, S., et al. (2017). Sleep, melatonin, and the menopausal transition: what are the links?https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5611767/Pineal region tumors diagnosis and treatments. (2021).https://www.cancer.gov/rare-brain-spine-tumor/tumors/pineal-region-tumorsSharan, K., et al. (2017). Regulation of bone mass through pineal‐derived melatonin‐MT2 receptor pathway.https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5575491/Shuboni, D. D., et al. (2016). The contribution of the pineal gland on daily rhythms and masking in diurnal grass rats, Arvicanthis niloticus.https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4893007/Tan, D. X., et al. (2018). Pineal calcification, melatonin production, aging, associated health consequences and rejuvenation of the pineal gland.https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6017004/Uz, T., et al. (2003). The pineal gland is critical for circadian period1 expression in the striatum and for circadian cocaine sensitization in mice.https://www.nature.com/articles/1300254Wirz-Justice, A. (2017). Seasonality in affective disorders [Abstract].https://www.ncbi.nlm.nih.gov/pubmed/28711512FEEDBACK:Medically reviewed by William C Lloyd III, MD, FACS — By Zawn Villines — Updated on August 21, 2022 Latest newsWhat sets 'SuperAgers' apart? Their unusually large neuronsOmega-3 may provide a brain boost for people in midlifeSeasonal affective disorder (SAD): How to beat it this fall and winterCDC: Monkeypox in the US 'unlikely to be eliminated in the near future'Why are more women prone to Alzheimer's? New clues arise Related CoverageHypophysectomy: What does it involve? A hypophysectomy is a procedure to remove the pituitary gland because there is a benign or malignant tumor present. This is a difficult procedure that…READ MOREAll you need to know about melatoninMedically reviewed by Raj Dasgupta, MD Melatonin is a hormone that helps to regulate daily body rhythms. It also fills many other roles and boasts a wealth of potential medical uses.READ MORECan you overdose on melatonin?Medically reviewed by Alyssa Peckham, PharmD, BCPP A melatonin overdose is is possible, but unlikely. However, there are possible side effects to its use. Learn more.READ MOREWhat to know about osteoporosisMedically reviewed by Brenda B. Spriggs, M.D., MPH, FACP Osteoporosis occurs when bone density decreases. This affects the structure and strength of bones and makes fractures more likely. Osteoporosis is…READ MORE