Melatonin is a hormone that the brain produces in response to darkness, and it helps with the timing of circadian rhythms (24-hour internal clock) . 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. Melatonin supplements promise sound, natural sleep and are even touted as a “miracle” for people with sleep disorders. Here are some of the uses and effectiveness of melatonin:

Likely 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.
• 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 dont seem to work.

According to practice guidelines from the American Academy of Sleep Medicine and the American College of Physicians, there’s not enough strong evidence on the effectiveness or safety of melatonin supplementation for chronic insomnia to recommend its use. Melatonin is generally safe for short-term use, and unlike with many sleep medications, with melatonin, you are unlikely to become dependent on it, have less ... . However, it is important to talk to a healthcare provider before taking melatonin, especially if you have diabetes, high blood pressure, or are pregnant or breastfeeding.