What is Melatonin?
Melatonin is the natural hormone your body secretes that helps to maintain your wake-sleep cycle (also called “biological clock”). The wake-sleep cycle is the process of sleep and wakefulness; in humans this averages 8 hours of nighttime sleep and 16 hours of daytime activity. Melatonin is also made synthetically and available without a prescription as an over-the-counter (OTC) dietary supplement in the U.S.
Endogenous melatonin release (melatonin made by our bodies) is increased each day in response to darkness, peaking between 11PM and 3AM at roughly 200 picograms (pg) per mL. Nighttime melatonin hormone levels are roughly 10 times higher than in the daytime. Levels fall sharply before daylight, and are barely detectable in the daylight hours. The rise and fall in endogenous melatonin levels signal wake and sleep times, known as our circadian rhythm.
Natural melatonin secretion starts from the amino acid tryptophan, with serotonin as an intermediary, and then is released to the melatonin receptors in the brain, eye and other areas to help control the sleep and wake cycles. The melatonin half-life is short, roughly 20 to 50 minutes. It is metabolized (broken down) by the CYP-450 enzyme system in the liver and then excreted in the urine or feces.
Shorter periods of melatonin production occur in the summer with longer days, and more prolonged periods of production occur in the winter. Light at night (such as from smartphones or the TV) blocks the production of melatonin and can lead to sleep disturbances. Age also suppresses the levels of nighttime melatonin that are released, which may contribute to the problem of insomnia and early awakening often seen in older adults.
Melatonin supplementation has been suggested to have many uses, from sleep disorders to cancer treatment , but robust studies are lacking for many uses. However, it has been widely studied for treatment of jet lag and other sleep disorders. Additional, early research to define melatonin suggests it has an anti-oxidative activity, a role in modulating immune responses, and possible anti-tumor activity.
Is Melatonin a Hormone?
Melatonin is a natural hormone when produced in the body (the endogenous hormone). Melatonin is not a vitamin. Melatonin supplements (exogenous hormone) are made synthetically and all products and strengths on the U.S. market are available without a prescription at the pharmacy, nutrition stores, and other retail shops.
Melatonin is most commonly used to:
- help decrease jet lag
- adjust sleep cycles in the blind (non 24-Hour Sleep Wake Disorder, or Non-24)
- treat shift-work sleep disorders in people with alternating work schedules
- for general insomnias (Poor sleep affects diabetes both directly and indirectly, by triggering changes to hormones, contributing to weight gain and obesity, and causing changes to behavior and lifestyle)
How Does Melatonin Work?
Natural melatonin is a highly lipid soluble hormone produced in the pineal gland in the brain. It is synthesized from the amino acid tryptophan and then released into the blood and cerebrospinal fluid, crossing the blood-brain barrier. It sends messages to the melatonin receptor agonist in the brain and other areas of the body to help control the sleep and wake cycles.
Does melatonin help you sleep? When taken as supplement, the function of melatonin is to mimic the effects of the natural hormone. Drowsiness generally occurs within 30 minutes after taking melatonin. However, taking melatonin right before bed may not be the best strategy for all sleep disorders. Ask your doctor about the best method of dosing melatonin. Melatonin does not work for everyone.
Before Taking This Medicine
Do not use melatonin if you are allergic to it.
Before using melatonin, talk to your healthcare provider. You may not be able to use this medication if you have certain medical conditions, such as:
- a bleeding or blood clotting disorder such as hemophilia
- taking a blood thinner like warfarin
- high or low blood pressure
- epilepsy or other seizure disorder
- if you are using any medicine to prevent organ transplant rejection
- an autoimmune condition
- using other sedatives or tranquilizers
It is not known whether melatonin will harm an unborn baby. Do not use this product without medical advice if you are pregnant.
High doses of this medicine may affect ovulation, making it difficult for you to get pregnant.
It is not known whether melatonin passes into breast milk or if it could harm a nursing baby. Do not use this product without medical advice if you are breast-feeding a baby.
Do not give any herbal/health supplement to a child without medical advice.
Melatonin for Sleep Disorders
Researchers have conducted many studies on melatonin supplements for various conditions. Most studies have been conducted in sleep disorders, such as jet lag, shift work sleep disorders, delayed sleep phase disorder, and insomnia. However, studies are often not consistent in their results and questions still remain about its usefulness, dosage, length of treatment and long-term safety for some sleep conditions.
Melatonin can be effective for jet lag for many people when dosed at the appropriate time. Melatonin effectiveness for insomnia might slightly hasten the amount of time needed to fall asleep, but may not increase the overall sleep time. Melatonin does appear to be safe for short-term use (less than three months).
Melatonin for Jet Lag:
- Eastbound: If you are traveling east, say from the US to Europe, take melatonin after dark, 30 minutes before bedtime in the new time zone or if you are on the plane. Then take it for the next 4 nights in the new time zone, after dark, 30 minutes before bedtime. If drowsy the day after melatonin use, try a lower dose.
- Westbound: If you are heading west, for example, from the US to Australia, a dose is not needed for your first travel night, but you then may take it for the next 4 nights in the new time zone, after dark, 30 minutes before bedtime. Melatonin may not always be needed for westbound travel.
Given enough time (usually 3 to 5 days), jet lag will usually resolve on its own, but this is not always optimal when traveling.
What Happens if I Miss a Dose of Melatonin?
If you miss taking a dose of melatonin, there is no cause for concern. However, melatonin may impair your thinking and reaction time. If you will be driving or doing any hazardous activity, skip your dose as melatonin can cause drowsiness.
Otherwise, use the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not use extra medicine or double your dose to make up the missed medication.
Can You Overdose on Melatonin?
Melatonin is thought to be very safe in the short-term with a low risk for overdose.
Melatonin Side Effects
Some people can have side effects from melatonin that may include:
- daytime drowsiness, dizziness, weakness, or confusion
- vivid dreams, nightmares
- feeling depressed, anxious, irritable
- loss of appetite, diarrhea, nausea, stomach pain
- blood pressure changes
- joint or back pain
- elevated risk for seizures
Melatonin and Pregnancy
Most dietary supplements like melatonin have not been studied in pregnant women, during breastfeeding, or in children. Seek advice from your healthcare provider before using any dietary supplement if you are pregnant, nursing, or considering the use of this product in a child under 18 years of age.
Melatonin Drug Interactions
Some important drug interactions can occur with melatonin even though it is a dietary supplement:
- Fluvoxamine (Luvox) – avoid with melatonin
- Sedative-type medications – avoid with melatonin
- Blood-thinner medications (anticoagulants) such as warfarin, heparin, or aspirin
- Medications for diabetes; blood sugar may increase with melatonin
Other drugs interactions exist. Check with your doctor before you take melatonin with any medication. It is also important your pharmacist screen for drug interactions with any new medication, including OTC supplements, herbals, and vitamins. Do not stop using any medications without first talking to your doctor.