What is the pineal gland?

The pineal gland is your body’s own internal timekeeper. It helps set your sleep patterns to coincide with day-night cycles, making you feel tired when it’s dark and alert during the day.

In this article, we explore how the pineal gland uses a sleep-inducing hormone called melatonin, and how you can make lifestyle changes to boost your sleep quality.

We cover:

• What is the function of the pineal gland?
• What hormone does the pineal gland make?
• What can go wrong with the pineal gland?
• What can affect melatonin levels?
• How to increase your melatonin levels
• Are melatonin supplements a good idea?

What is the function of the pineal gland?
 

The pineal is a tiny, pine-cone-shaped gland, located deep in the centre of your brain. It works closely with your body’s circadian rhythm (another term for your internal body clock) to regulate your sleep/wake cycle.

The pineal is sometimes referred to as the third eye as, like your eyes, it responds to light and dark. At night, the pineal gland releases a hormone that helps you drift off to sleep, and then reduces its production in the morning to help you wake up.

The pineal gland is part of the endocrine system that controls hormone levels to regulate most of your body’s processes.

What hormone does the pineal gland make?
 

The main hormone made by the pineal gland is melatonin. It’s often called the sleep hormone, as it helps set your sleep pattern to coincide with day-night cycles.

Raised levels of melatonin at night help calm your body in preparation for sleep. During daylight hours, melatonin levels decline, making you feel alert and ready to face the day.

Studies suggest that melatonin may also have non-sleep-related functions. The presence of melatonin receptors throughout the body, including in the cardiovascular, reproductive, and immune systems, supports this.

Melatonin may help protect against heart-related conditions, such as atherosclerosis (narrowing of the arteries due to fatty plaques) and high blood pressure [1]. And research has linked it to antitumour activity in cancer [2].

However, more research is needed to better understand how the pineal gland and melatonin work.

What can go wrong with the pineal gland?
 

Some health conditions can affect the pineal gland’s ability to make melatonin. This can lead to hormone imbalances that may impact your sleep.

Conditions that affect the pineal gland include [3]:

• Craniopharyngiomas — rare, non-cancerous brain tumours.
• Injury to the pineal gland
• Pineal tumours
• Rare genetic disorders

However, there are many, more common conditions that can affect your sleep pattern. Environmental and lifestyle factors also play a part.

Most sleep problems are related to poor sleep hygiene—a set of habits that can affect your sleep quality. So, there’s a lot you can do to improve your sleep naturally.

If you’re having trouble sleeping, the NHS has some great advice on falling asleep faster and sleeping better. The Sleep Charity is also a good source of information and support.

If you’re still having problems after making healthy changes, we recommend you see your doctor to explore the possible causes.

What can affect melatonin levels?
 

Many factors including lifestyle choices and the environment can cause low melatonin levels. This can make it difficult for you to fall asleep and affect your sleep quality.

Melatonin levels can be affected by:

• Ageing—melatonin levels naturally decrease as you get older, which may lead to poorer sleep quality [4].
• Disrupted light/dark cycles—scrolling on your phone in bed may seem harmless, however, electronic devices emit blue light that can play havoc with your melatonin levels.
• Drinking alcohol—despite having a sedative effect, alcohol is known to disrupt your natural sleep cycle.
• Caffeinated drinks before bed—although your morning coffee can help you feel ready to take on the day, caffeinated drinks at bedtime can reduce your melatonin level, affecting your sleep quantity and quality [5].

How to increase your melatonin levels
 

You can take steps to improve your melatonin levels by making simple diet and lifestyle changes.

Three tips for boosting melatonin levels naturally:

1. Avoid caffeinated drinks or alcohol before bed—try warm milk, herbal tea, or a glass of water instead to avoid disruption to your sleep/wake cycle.
2. Limit artificial light—exposure to artificial light before bed may interfere with melatonin production. So, leave electronic devices like smartphones, laptops, and TVs out of the bedroom. Black-out blinds are another great tip for a good night's sleep.
3. Eat tryptophan-rich foods—tryptophan is an essential amino acid that helps your body make melatonin.

Good sources of tryptophan include:

• Chicken and turkey
• Dairy products
• Eggs
• Peanuts
• Pumpkin and sesame seeds
• Fish
• Tofu and soy

Practising good sleep hygiene is also a great way to keep your sleep/wake cycle in sync. This includes keeping a consistent schedule for sleeping and waking—even on weekends.

Are melatonin supplements a good idea?
 

Doctors and specialists sometimes recommend taking a melatonin supplement for short periods to treat sleep disorders like insomnia.

Melatonin supplements boost your body’s natural melatonin level. They may help you fall asleep more quickly and stop you waking up through the night. Supplements may also help reset your sleep/wake cycle if you have jet lag.

However, melatonin supplements are only prescribed in certain cases. If you’re having trouble sleeping, your doctor will usually advise lifestyle changes and focusing on good sleep hygiene in the first instance.

In the UK, melatonin is available on prescription only. But in many other countries, including the US, it’s freely available in health food shops and online.

The NHS warns against ordering this supplement online for safety reasons. Melatonin supplements aren’t suitable for everyone.

To make sure it’s safe for you, tell your doctor or pharmacist if you have [6]:

• An autoimmune condition, such as rheumatoid arthritis or lupus
• Experienced an allergic reaction to melatonin or another medicine
• Liver or kidney problems

Experts do not usually recommend melatonin supplements during pregnancy because little is known about their effects on babies [7].

Can my melatonin levels be too high?
 

It’s possible to have higher-than-normal night-time melatonin levels, but it’s much less common than having low levels.

Taking too much supplementary melatonin is the most common cause of high melatonin levels. However, it’s rarely caused by certain medical conditions.

These include polycystic ovary syndrome (PCOS) and hypogonadotropic hypogonadism—a form of hypogonadism where the ovaries or testes make little or no sex hormones because of a problem with the hypothalamus or pituitary gland.

Learn more about your hormone health
 

You can learn more about the endocrine glands, hormones, and the processes they control in your body in our Hormone Health Hub.

If you want to check your hormone levels and aren’t sure where to start, read our Female Hormone Blood Test Buying Guide or Male Hormone Blood Test Buying Guide.

References

1. Sun, H., Gusdon, A.M., and Qu, S. (2016) Effects of melatonin on cardiovascular diseases: progress in the past year. Curr Opin Lipidol, 27(4):408-13. doi: 10.1097/MOL.0000000000000314. PMID: 27075419; PMCID: PMC4947538.
2. Straif, K., Baan, R., Grosse, Y., Secretan, B., El Ghissassi, F., Bouvard, V., Altieri, A., Benbrahim-Tallaa, L., Cogliano, V. (2007) WHO International Agency for Research on Cancer Monograph Working Group. Carcinogenicity of shiftwork, painting, and firefighting. Lancet Oncol, 8(12):1065-6. doi: 10.1016/S1470-2045(07)70373-X. PMID: 19271347.
3. Arendt, J., Aulinas, A. Physiology of the Pineal Gland and Melatonin. [Updated 2022 Oct 30]. In: Feingold, K.R., Anawalt, B., Blackman, M.R., et al., editors. Endotext [Internet]. South Dartmouth (MA): MDText.com, Inc.; 2000. Available at: https://www.ncbi.nlm.nih.gov/books/NBK550972/
4. Scholtens, R.M., van Munster, B.C., van Kempen, M.F., and de Rooij, S.E. (2016) Physiological melatonin levels in healthy older people: A systematic review. J Psychosom Res, 86:20-7. doi: 10.1016/j.jpsychores.2016.05.005. Epub 2016 May 10. PMID: 27302542.
5. Shilo, L., Sabbah, H., Hadari, R., Kovatz, S., Weinberg, U., Dolev, S., Dagan, Y., and Shenkman, L. (2002) The effects of coffee consumption on sleep and melatonin secretion. Sleep Med, 3(3):271-3. doi: 10.1016/s1389-9457(02)00015-1. PMID: 14592218.
6. NHS (2023) Who can and cannot take melatonin. Available at: https://www.nhs.uk/medicines/melatonin/who-can-and-cannot-take-melatonin/ [Accessed 10 September 2024].
7. NHS (2023) Pregnancy, breastfeeding, and fertility while taking melatonin. Available at: https://www.nhs.uk/medicines/melatonin/pregnancy-breastfeeding-and-fertility-while-taking-melatonin/ [Accessed 10 September 2024].