Melatonin is a hormone in the body that is responsible for regulating when we sleep and when we wake. Another name for this is circadian rhythm--or internal clock. The body makes more melatonin when it's dark and less when it's light. Having trouble sleeping could be caused by low amounts of melatonin in the body. Too much light in the evening or too little in the daytime can upset circadian rhythm.[1,2]
Melatonin also has a hand in controlling reproductive hormones, including when a woman starts and stops menstruating. And, levels of the melatonin may be linked to aging.
The medication form of melatonin is usually made in a lab setting. Melatonin comes in a variety for forms including pills, capsules, cream and lozenges.[1,2]
Update: Melatonin has made it to our Best Sleep Aid guide! If you're looking for general sleep supplement advice, including the best products and other ingredients to try alongside melatonin, click the link to read the info on our blog.
What Is Melatonin Used For?
People use melatonin for many medical purposes, from osteoporosis and menopause to Alzheimer's disease and cancer, but mostly for regulating the body'sinternal clock and insomnia. People who are blind, do shift work and travel over several time zones especially need assistance with internal clock regulation.
Insomnia can occur because of worry or stress, use of certain medications and the presence of developmental disorders. Melatonin is also used as sunscreen.  Although the usual dose is 1 to 3 milligrams, dosages and length of therapy vary widely depending upon age and diagnosis. Consult your doctor regarding what is best for your circumstances. 
Does Melatonin Work? The Melatonin Benefits
Melatonin seems to work well for people who have trouble sleeping. Specifically, children with autism and mental retardation, and people with insomnia, jet lag, and cluster headaches. It also may help people sleep who are trying to quit smoking, have pre-surgery anxiety, have come off benzodiazepines (sedatives, muscle relaxants, hypnotics), or are blind and suffering withsleep disorders.
It also may help lessen the severity of sunburn, symptoms of tardive dyskinesia, a movement disorder, and symptoms of fibromyalgia. Low levels of melatonin in the body could spur some types of breast cancer as well as prostate cancer. But, evidence indicates that melatonin may be helpful in treating breast and prostate cancers by stunting the cells. [1 and 2]
Melatonin works for most of its intended uses:
As a sleep aid:
- A meta-analysis across 17 different studies showed that melatonin treatment significantly reduced sleep onset latency by 4.0 min; increased sleep efficiency by 2.2%, and increased total sleep duration by 12.8 min. Most of those studies were done on healthy individuals.
- In elderly and Alzheimer's patients, a significant improvement of sleep quality was found, while there were no significant differences between initial and final neuropsychological evaluation.
- Melatonin has been shown to reduce jetlag and get you back on a normal schedule: Melatonin is remarkably effective in preventing or reducing jet-lag, and occasional short-term use appears to be safe. It should be recommended to adult travelers flying across five or more time zones, particularly in an easterly direction. It also gives very good instructions on how to use melatonin to prevent jetlag.
- However, this study says the opposite with "secondary sleep disorders" such as jetlag or working the night-shift: There is no evidence that melatonin is effective in treating secondary sleep disorders or sleep disorders accompanying sleep restriction, such as jet lag and shiftwork disorder. There is evidence that melatonin is safe with short term use... only one way to find out!
As an Antioxidant:
- Melatonin also synergizes with vitamin C, vitamin E and glutathione in the scavenging of free radicals.
- This review briefly summarizes the multiple actions by which melatonin reduces the damaging effects of free radicals and reactive oxygen and nitrogen species.
List Provided by Mike
Where it's Less Effective or Not Enough Evidence
Meanwhile, research indicates that melatonin is less effective in helping people adjust to shift work and those with depression. In fact, melatonin may intensify the symptoms of depression.  And, there is not enough evidence to support melatonin's use for: 
- Insomnia connected to the use of beta-blockers
- Menopausal symptoms
- Improving sleep in children with Attention Deficit-Hyperactivity Disorder
- Migraines and other headaches
- Irritable Bowel Syndrome
- Birth control
More research is needed. Contact your doctor before self-treating symptoms with melatonin.
Are There Any Drug Interactions Associated with Melatonin?
Melatonin interacts with many medications. Do not mix melatonin with the following: [1 and 2]
- Sedatives: Both melatonin and sedatives can cause drowsiness, heightening the effect.
- Birth control pills: Birth control pills have a hand in the amount of melatonin the body makes, so if you're taking them along with melatonin supplements, you could end up with an overdose.
- Diabetes medication: This medication lowers the amount of blood sugar while melatonin increases it, so the latter may alter the effectiveness of diabetes medication.
- Caffeine: Caffeine may affect how melatonin supplements work.
- Immunosuppressants: Melatonin stimulates the immune system, so it may alter the effectiveness of medication meant to slow it down.
- Blood pressure medication: This medication may not work as well when taken along with melatonin.
- Anticoagulants/Antiplatelets: These drugs, as well as melatonin, inhibit clotting, so taking them together may boost the risk of bleeding.
- Verapamil: This medication may speed up the body's melatonin processing and, thus, influence the effectiveness of it.
- Flumazenil: This medication may alter the effects of melatonin.
This is not an exhaustive list. If you're taking any medication, consult your health care provider before taking melatonin.
What Are the Side Effects?
Side effects that may occur with Melatonin include:
- Daytime sleepiness
- Lower sperm count
- Increased breast size (in men)
- Decreased sex drive
Are There Any Safety Issues and Considerations I Should Be Aware Of?
- Follow all directions for supplement use, including melatonin.
- Supplements can act like drugs if they are used in large amounts. Take as directed.
- Inform your health care provider of all supplements and complementary care you use. Discuss proper dosages particular to your symptoms and medical history.
- Melatonin is safe for most adults if taken short-term. 
- Do not drive or operate machinery within four to five hours after taking melatonin. 
- Do not take melatonin is you are pregnant or breastfeeding. 
- Consult your child's physician before administering it to them. 
- Melatonin can heighten the symptoms of depression; do not use with antidepressants. 
- There is an increased risk of stroke with the use of melatonin. 
- Individuals age 65 and older should consult a physician before taking melatonin.
- Women in peri- or post-menopause should use melatonin on a short-term basis only. 
- Herbs and other supplements are not strictly regulated by the government. Product safety and consistency are not guaranteed. Effects may vary according to brand and batch.
- Purchase melatonin from companies you trust, who have a good reputation.
- Don't take our word for it. Consult other reputable sources such as scientific journals for information on melatonin and any other complementary or alternative treatment before experimenting with it. Educate yourself about what you put into your body!
- Regular exercise, a balanced diet and an overall healthy lifestyle can have a significant, positive effect on your mental and physical state.
- Although we don't sell melatonin, you can compare quality and price of a variety of brands here at PricePlow.com. Please note that we are not doctors. We take no responsibility for the products listed here since we do not manufacture them.
What Dosage is Best?
Talk to your doctor before beginning any diet or supplementation program. Most supplements contain 3mg, which is also where most studies are focused. 1-3mg is the dosage to use, and you should not constantly use this -- it's a hormone! Cycle off and never rely on hormonal supplements for long-term support.
What is the Best Product?
It's so cheap that you should just find whatever brand you like and trust the best to give it a try. Just make sure you're not spending too much - this stuff is readily available for less than $10 nearly everywhere when it's not dosed with anything else. Look for GMP certification on the label if you're not sure.
Where to Buy Supplements Like Melatonin
Melatonin is so cheap, you should have no problem getting a good product at any local store.
But if you're going to be buying more expensive supplements, such as other sleep aids, you should definitely shop online. With this site (PricePlow.com), you typically save over 35% off retail prices because we send you to the cheapest store for each product!