Melatonin treatment: what are the long-term effects?

Melatonin is a natural hormone produced by the pineal gland (or epiphysis) located in the centre of the brain, from its precursor tryptophan. Other organs such as the retina, the digestive system and certain blood cells also produce melatonin in smaller quantities.

In practical terms, the level of brightness perceived by our retina, the light-sensitive part of the eye, is transmitted to our hypothalamus, the part of the brain that acts as our internal clock. This small structure in the nervous system then relays the information to the pineal gland, which is responsible for secreting melatonin.

Melatonin's main role is to make us drift off to sleep after dark and to regulate our 24-hour sleep-wake cycle, also known as the circadian rhythm. Here's an overview of its functions in the human body:

1. Synchronising circadian rhythms: Melatonin helps synchronise the body's internal biological clock with the circadian rhythm, the 24-hour cycle governed by the natural alternation of light and darkness. It also plays an essential role in regulating physiological functions such as body temperature, blood pressure and the cascade of other hormones.

2. Sleep-wake alternation: Levels of melatonin, also known as the 'sleep hormone', play an important role in the transition from wakefulness to sleep and vice versa. Melatonin production increases at the end of the day, when light levels fall, signalling to the body that it is time to prepare for sleep. Its concentration in the blood is multiplied by 10 during the night, reaching its peak at around 3 or 4 in the morning before falling gently to its minimum at the moment of waking. When we get up, cortisol takes over to wake us up!

3. Antioxidant: Melatonin also acts as a powerful antioxidant in the body, helping to protect cells from damage caused by free radicals. The molecule can help protect cells from oxidative stress, boost the immune system and maintain tissue health and function.

4. Effects on mental health: Some research suggests that melatonin may have beneficial effects on mental health, particularly by helping to reduce anxiety and depression. However, research into the use of melatonin in the treatment of depression is still ongoing and there is no certainty in this area. What's more, the Anses (French National Health and Safety Agency) does not recommend melatonin as an antidepressant.

Melatonin fulfils multiple important functions in the body, from regulating sleep to modulating circadian rhythms and cell protection.

Prolonged use of melatonin is not generally dangerous, but we advise you to use it only occasionally. What's more, you should avoid creating a dependency. Once the sleep-wake balance has been restored, there is no point in continuing the treatment.

When it's time to stop taking melatonin, it's essential to proceed with caution, to talk to a healthcare professional (GP, pharmacist) and to stop taking it gradually to avoid the unpleasant symptoms that would result from stopping this supplement abruptly. A few precautions to take:

1. Consult your GP: If you have started taking melatonin for a sleep problem, talk to your doctor before stopping. He or she will be able to advise you, based on the state of your sleep and your medical history.

2. Gradually reduce the dose: If your doctor advises you to stop taking melatonin, start by reducing the amount each evening over a period of multiple days/weeks, until you no longer need it. This allows your body to adapt gradually to the reduction to the natural level of melatonin, whereas stopping too abruptly could cause real difficulties in falling asleep.

3. Monitor your symptoms: While you're reducing or stopping melatonin, monitor the quality of your sleep, bearing in mind that your body needs time to readjust. That said, if your sleep problems persist for a few weeks after stopping treatment, feel free to consult a healthcare professional.

4. At the same time, try other natural solutions: As you gradually lower your melatonin levels, it's a good idea to explore other techniques and solutions for improving the quality of your sleep, such as aromatherapy, relaxation exercises, regular physical exercise, a consistent sleep routine, and creating a sleep-friendly environment in your bedroom.