Melatonin is mostly secreted during hours of darkness, and is thought to regulate sleep patterns and other body processes that depend on the time of day, or the time of year. Because of this, it has sometimes been used to promote sleep and reduce the unpleasant effects of jet lag, following long-haul flights; to regulate sleep for people undertaking shift work; and to alleviate insomnia (sleeplessness) in other groups of patients.
Some specialist doctors have tested or recommended Melatonin for other medical conditions, such as sleep disturbances in autism, migraines and other headaches, and seasonal affective disorder (SAD).
In the UK, all forms of Melatonin are prescription-only medicines, and are only available from a pharmacy when they have been prescribed by a registered doctor.
In the UK, there is only one licensed medicine containing Melatonin, called "Circadin Tablets" (each containing Melatonin 2mg in a modified-release tablet), which is recommended for the short-term treatment of insomnia in adults over 55 years.
Other Melatonin preparations (such as Melatonin tablets in different strengths, or Melatonin capsules) are classed as "unlicensed" medicines in the UK. They can be supplied by a pharmacy when you have a valid prescription, but the doctor has a greater responsibility for the safety of the medicine.
Melatonin is generally considered to be safe, but there are some people who should not take it, including women who are pregnant or breast feeding, people with certain medical conditions such as high blood pressure, poorly controlled diabetes, depression, or epilepsy. It is not compatible with certain other medicines, such as drowsy medicines for sleeplessness, warfarin and other anti-coagulants, and medicines that affect the immune system. It's important to list all of your medical conditions and other medicines you are taking when you complete our medical questionnaire.
How to use Melatonin
The recommended dose of Melatonin (usually between 0.5mg and 5mg) is recommended to be taken at bedtime. For jet lag, this dose is usually taken on the day of arrival at the destination, and then continued for between 2 and 5 days. The same routine is followed when you return home.
Melatonin Side Effects
Following recent clinical trials for the UK branded medicine "Circadin" (melatonin 2mg modified-release tablets), no side effects were identified that could be classed as "very common" or "common" (where there is an estimated chance of a side effect of at least 1 in 100). Some side effects were identified as "uncommon" (between a 1 in 100 and 1 in 1000 chance) including irritability, insomnia or sleepiness, headaches, and stomach pain. This would also be expected to be the pattern of side effects for other melatonin preparations.
For a full list of potential side effects and other important information, please read the patient leaflet provided in the pack before starting any course of treatment. The leaflet can also be viewed online here.