Melatonin is a natural hormone produced by the pineal gland – also called the pineal gland or epiphysis – in the brain and then released into the bloodstream. Darkness causes the pineal gland to start producing melatonin, while light causes the production of the hormone to stop.
Melatonin is a hormone that signals the body that it is time to sleep. In people who do not have sleep problems, the body follows a sleep-wake cycle of about 24 hours. This cycle is technically known as the circadian rhythm. Melatonin helps regulate the circadian rhythm, which means that the human sleep-wake cycle is brought into line with the day-night cycle. In this way, melatonin makes it easier to fall asleep and promotes consistent, high-quality and sustained rest.
Changes in light and temperature help the body feel tired. The brain releases melatonin when it is dark. Exposure to light can block the production of melatonin, which is why it is important to sleep in a dark room. Light from computer and television screens can also suppress the body’s natural melatonin production, disrupting sleep. Similarly, people who sleep during the day because they work at night may not produce melatonin when it is time to sleep.
In addition to regulating sleep-wake cycles, research suggests that melatonin has important cognitive and developmental functions. It is known that people produce the most melatonin around the age of three. Melatonin production steadily decreases with age. People aged 70 and over have about a quarter of the amount of melatonin in their system during sleep as teenagers.
Melatonin, which is naturally produced by the human body, is also known as endogenous melatonin. However, the sleep hormone can also be synthesised artificially in a laboratory. Such exogenous melatonin is sold today mainly as food supplements usually in the form of pills, capsules, chewable tablets or liquids.
Melatonin-containing supplements can improve sleep by increasing melatonin levels in people whose bodies cannot produce enough of this hormone. These supplements can also improve sleep in people who produce enough melatonin but have difficulty falling asleep for other reasons.
The ideal dosage for melatonin varies from person to person and is typically between 1 mg and 5 mg. Various factors such as a person’s body weight, metabolism and general health can also affect how their body responds to melatonin. Ideally, supplements containing melatonin should be taken about an hour before going to bed.