Melatonin is a hormone secreted by the brain's pineal gland that plays a critical role in sleep. It maintains the human
body’s circadian rhythm (the internal body clock) and assists in the regulation of other hormones. The production and
release of melatonin increases in the evening with darkness and decreases in the morning with natural light.
Melatonin levels in the blood are highest before bedtime and remain elevated for about 12 hours
throughout the night before the morning light causes a drop to lower daytime levels. During
the shorter days of the winter months, the body may produce melatonin either earlier or later in the day
Exposure to artificial light at night or a lack of light during the day will disrupt the body's normal melatonin cycles and block the production of melatonin at night. International travel and late night shift work are known to disrupt melatonin cycles.
Melatonin also plays a role in the timing and release of female reproductive hormones. It helps determine
when a woman first starts menstruating and stops menstruating (menopause), as well as the frequency
and duration of menstrual cycles.
The strongest evidence supporting the use of melatonin is for delayed sleep phase syndrome, insomnia in
children and the elderly, jet lag, and sleep problems in people with behavioral, developmental, or mental
Delayed sleep phase disorder
Delayed sleep phase disorder is a disruption of the body’s biological clock in which a person’s sleep-wake timing
cycle is delayed by 3 to 6 hours. Adults and teens with this sleep disorder have trouble falling asleep before
2 a.m. and have trouble waking up in the morning. Studies show that melatonin may help to decrease the amount
of time it takes to fall asleep.  In a 2007 clinical practice guideline, the American Academy of Sleep Medicine
timed melatonin supplementation for this sleep disorder. 
Insomnia in children and the elderly
Research indicates that melatonin may benefit children and the elderly with insomnia. 
Jet lag is caused by rapid travel across several time zones. Its symptoms include disturbed sleep, daytime
fatigue, indigestion and a general feeling of discomfort.
According to its 2007 clinical practice guidelines, the American Academy of Sleep Medicine supports using
melatonin to reduce jet lag symptoms and improve sleep after traveling across more than one time zone. 
Sleeping problems in children with autism and intellectual disabilities
Children and adolescents with intellectual disabilities, autism, and other central nervous system disorders may
benefit from melatonin. It may be helpful for disturbed sleep-wake cycles and for decreasing the time it takes
to fall asleep. 
Insomnia in healthy people
Some people who have insomnia appear to have lower melatonin levels. Supplementing with melatonin may help
them sleep. Evidence suggests that melatonin decreases the time it takes to fall asleep, as well as improves
sleep quality and sleep duration. Melatonin may also be beneficial for daytime sleep. 
Shift work disorder
People who work afternoon to nighttime or nighttime to early morning hours may be affected by shift work
disorder. Melatonin may improve daytime sleep quality and duration. The American Academy of Sleep Medicine
recommends taking melatonin prior to daytime sleep for night shift workers with shift work disorder to enhance
daytime sleep. 
Melatonin may also possibly be effective for: 
Cluster headaches (10 mg per night).
Low blood platelets (thrombocytopenia).
Improving the effectiveness of certain cancer medications used to fight tumors in the breast, lung,
kidney, liver, pancreas, stomach, colon, prostate, and decreasing some side effects of cancer
Decreasing symptoms of a movement disorder called tardive dyskinesia (TD).
Helping decrease symptoms in people who are quitting smoking.
Melatonin seems to reduce anxiety, restlessness, irritability, depression, and cigarette craving.
A reduction of these symptoms occurs over the next 10 hours when a single oral dose of 0.3 mg
of melatonin is taken 3.5 hours after stopping cigarettes.
Helping strengthen the immune system
Preliminary evidence suggests this due to melatonin’s strong antioxidant effects. 
Although there is less scientific evidence supporting the effectiveness, some people use melatonin for Alzheimer’s
disease, ringing in the ears, depression, chronic fatigue syndrome (CFS), fibromyalgia, migraine and other
headaches, irritable bowel syndrome (IBS), bone loss (osteoporosis), epilepsy, insomnia due to beta-blockers
(high blood pressure medication),menopause, birth control and an anti-aging agent. 
Side effects of melatonin are uncommon but can include drowsiness, headache, dizziness, or nausea. There
have been no reports of significant side effects of melatonin in children. 
When buying any dietary supplement, it’s important to buy from a brand name manufacturer. Vitamin Grocer offers a variety of melatonin supplements from such brand names as Natrol, Source Naturals, Twinlab, Schiff, Optimum Nutrition,
Nutricology and Country Life. You also need to choose a delivery form that best suits your personal preferences. Choices
include capsules, tablets, sublinguals, dots, liquid and even lozenges. Most importantly, you need to find the dosage and
absorption speed that best suits your needs. The available delivery forms will vary according to the dosage and absorption
speed of the supplement. Below is a quick primer on choosing the right melatonin supplement for you.
Melatonin supplements are available in dosages ranging from 1 milligram to
10 milligrams. A 10 milligram dosage is generally considered "maximum strength".
It is recommended that consumers test their tolerance for melatonin with a 1 or 3
milligram dosage before moving on to the higher dosages.
Rapid Release/Fast Dissolve
Melatonin supplements are available in rapid release or fast dissolve formulations in order to increase the speed of absorption into your system. These formulations are useful when you've been struggling to get to sleep and it's getting late. The rapid absorption speed of these formulations will help you get to sleep quickly and stop missing out on precious hours of sleep.
Some melatonin users report that while melatonin does help them to get to sleep, it does
not help them stay asleep. After a few hours of sleep, they wake up again and struggle with
the same restlessness. Time release or controlled release formulations solve this problem by
allowing for a gradual release of the active ingredient over a 4-6 hour period.
Melatonin can also be combined with other ingredients to create advanced sleep-inducing formulas. The most common supplementary ingredients found in these advanced formulations are calcium, magnesium, theanine and valerian root. When ingested together, calcium and magnesium can calm nerves and induce muscle relaxation. Theanine is an amino acid derivative of glutamine found in green tea which can contribute to a calm mental state. Valerian root is an herbal supplement known to have a sedative effect. Formulations with a combination of these ingredients can be more effective than melatonin alone for some individuals.
Sleep Disorder Resources
NHS Choices Sleep Guide: The National Health Service's
online information guide on conditions, treatment, local services and healthy living.
National Sleep Foundation: An independent, non-profit organization in the USA whose objectives
are to improve public health and safety by achieving understanding of sleep and sleep disorders, and to support
sleep-related education, research and advocacy.
Royal College of Psychiatrists: The
professional medical body responsible for supporting psychiatrists throughout their careers, from training through to
retirement, and in setting and raising standards of psychiatry in the United Kingdom.
National Health Service, Sleep Self-Assessment: Take
this short assessment, get a sleep score and get some practical tips and advice on what to do next. In association with
Sleepio, the online cognitive behaviour therapy programme designed to help sleep problems.
SleepEducation.com: A sleep health information resource by the American Academy
of Sleep Medicine.
NHS Melatonin Medicine Guide:
The National Health Service’s online source for comprehensive information about medicines, including known possible
side effects, interactions and dosages.