Melatonin

What is it?

Melatonin is a hormone made in the body. It regulates night and day cycles or sleep-wake cycles. Melatonin in supplements is usually made in a lab.

Darkness triggers the body to make more melatonin, which signals the body to sleep. Light decreases melatonin production and signals the body to be awake. Some people who have trouble sleeping have low levels of melatonin. It’s thought that adding melatonin from supplements might help them sleep.

People most commonly use melatonin for insomnia and improving sleep in different conditions, such as jet lag. It is also used for depression, chronic pain, dementia, and many other conditions, but there is no good scientific evidence to support most of these uses. There is also no good evidence to support using melatonin for COVID-19.

Is it effective?

NatMed Pro rates effectiveness based on scientific evidence according to the following scale: Effective, Likely Effective, Possibly Effective, Possibly Ineffective, Likely Ineffective, Ineffective, and Insufficient Evidence to Rate.

Probably Effective for …

Trouble falling asleep at a conventional bedtime (delayed sleep phase syndrome). Taking melatonin by mouth seems to shorten the time needed to fall asleep in young adults and children with this condition.
Non-24-hour sleep wake disorder. Taking melatonin by mouth at bedtime seems to improve sleep in children and adults who are blind.

Possibly Effective for …

Sleep disturbance caused by certain blood pressure medicine (beta blocker-induced insomnia). Taking melatonin by mouth might reduce sleep problems in people taking beta-blocker drugs.
Cancer. Taking high doses of melatonin by mouth or as a shot, administered by a healthcare provider along with chemotherapy or other cancer treatments, might reduce tumor size and improve survival rates in some people with cancer.
Confusion and agitation after surgery. In children receiving a medication called sevoflurane during surgery, taking melatonin by mouth before anesthesia might help to prevent anxiety and agitation while waking up. The effect of taking melatonin in adults undergoing surgery is unclear.
High blood pressure. Taking the controlled-release form of melatonin by mouth before bedtime seems to lower blood pressure in people with high blood pressure. Immediate-release products don’t seem to work.
Insomnia. Taking melatonin by mouth, short-term, seems to shorten the time it takes to fall asleep in people with insomnia, but only by about 7-12 minutes. It’s not clear if it affects the amount of time spent sleeping. It also seems to be more helpful in older adults and those with certain other conditions.
Jet lag. Taking melatonin by mouth can improve certain symptoms of jet lag such as alertness and reduce daytime sleepiness and tiredness. But it might not help shorten the time it takes for people with jet lag to fall asleep.
Migraine. Taking melatonin by mouth before bed can prevent migraines in adults and children. It’s not clear if melatonin helps to treat migraines.
Anxiety before a procedure. Taking melatonin by mouth or under the tongue somewhat reduces anxiety before surgery in adults. It’s not clear if it helps in children.
Sedation before a procedure. Taking melatonin by mouth might reduce the amount of sedatives needed for some medical procedures in children.
Sunburn. Applying melatonin gel to the skin before sun exposure seems to help prevent sunburn.
A group of painful conditions that affect the jaw joint and muscle (temporomandibular disorders or TMD). Taking melatonin by mouth at bedtime for 4 weeks reduces pain in females with jaw pain.
Low levels of platelets in the blood (thrombocytopenia). Taking melatonin by mouth can improve low blood platelet counts associated with cancer, cancer treatment, and other disorders.

Possibly Ineffective for …

Athletic performance. Taking melatonin by mouth shortly before resistance exercise or cycling doesn’t appear to improve performance.
Involuntary weight loss in people who are very ill (cachexia or wasting syndrome). Taking melatonin by mouth doesn’t improve appetite, body weight, or body composition in people with wasting syndrome from cancer.
Tiredness in people with cancer. Taking melatonin by mouth doesn’t seem to improve tiredness in people with cancer.
Pain in people with cancer. Taking melatonin by mouth doesn’t seem to reduce pain in people with cancer.
Critical illness (trauma). Taking melatonin by mouth doesn’t seem to shorten hospital stay in people that are critically ill.
Diseases, such as Alzheimer disease, that interfere with thinking (dementia). Taking melatonin by mouth doesn’t improve behavior or affect symptoms in people with Alzheimer disease or other forms of memory loss. But it might reduce confusion when the sun goes down in people with these conditions.
Inability to become pregnant within a year of trying to conceive (infertility). Taking melatonin by mouth doesn’t seem to improve pregnancy rates in females undergoing fertility treatments.
Sleep disorder due to rotating or night shifts (shift work disorder). Taking melatonin by mouth doesn’t seem to improve sleeping problems in people who do shift work.

Probably Ineffective for …

Withdrawal from drugs called benzodiazepines. Taking melatonin by mouth at bedtime doesn’t reduce withdrawal symptoms in people with insomnia who have stopped taking these drugs.
Depression. Taking melatonin by mouth doesn’t seem to reduce symptoms of depression, and might make symptoms worse in some people.

There is interest in using melatonin for a number of other purposes, but there isn’t enough reliable information to say whether it might be helpful.

Is there concern for the safety of its use?

When taken by mouth: Melatonin is likely safe for most adults when used short-term. Melatonin is possibly safe when taken long-term. It’s been used safely for up to 2 years. But it can cause some side effects including headache, sleepiness, dizziness, and nausea. Don’t drive or use machinery for 4-5 hours after taking melatonin.

When applied to the skin: Melatonin is likely safe for most adults when used short-term.

Special Precautions & Warnings:

Pregnancy: Melatonin is possibly unsafe when regularly taken by mouth or in high doses while trying to become pregnant. Melatonin might have effects similar to birth control, making it more difficult to become pregnant. There isn’t enough reliable information to know if melatonin is safe to use when pregnant. Until more is known, it’s best not to use melatonin while pregnant or trying to become pregnant.

Breast-feeding: There isn’t enough reliable information to know if melatonin is safe to use when breast-feeding. Stay on the safe side and avoid use.

Children: Melatonin is possibly safe when taken by mouth, short-term. Melatonin is usually well tolerated when taken in doses up to 3 mg daily in children and 5 mg daily in adolescents. There is some concern that melatonin might interfere with development during adolescence. Melatonin should only be used in children with a medical need. There isn’t enough evidence to know if melatonin is safe in children when taken by mouth, long-term.

Bleeding disorders: Melatonin might make bleeding worse in people with bleeding disorders.

Depression: Melatonin can make symptoms of depression worse.

High blood pressure: Melatonin can raise blood pressure in people who are taking certain medications to control blood pressure. Avoid using it.

Seizure disorders: Using melatonin might increase the risk of having a seizure.

Transplant recipients: People who have had a transplant often take medications to suppress the immune system. Melatonin can increase immune function. This might interfere with the effects of some transplant medications.