Melatonin is a hormone supplement used to manage sleep disorders and support the body's natural circadian rhythm.
Melatonin is a naturally occurring hormone that helps regulate the body’s sleep-wake cycle. It belongs to a group of substances known as chronobiotics, which influence the timing of biological rhythms. In many over-the-counter products, melatonin is added to support the body’s own sleep signals, especially when normal patterns are disrupted. You’ll find melatonin as the active ingredient in medicines such as Meloset, Sleepose and Restfine.
A number of products marketed in Hong Kong incorporate melatonin, each offered in slightly different forms.
All three are sold as generic-type preparations, though they may appear under various brand names in pharmacies. The strengths range from 0.5 mg to 5 mg per dose, and each product is approved for sale by the Hong Kong Department of Health.
Melatonin is most often used for conditions that involve difficulty falling or staying asleep. Common situations include:
The hormone works by signalling to the brain that it is nighttime, helping to align the body’s rhythm with the intended bedtime. While melatonin is widely used for these purposes, each individual’s response can vary.
When darkness falls, the brain’s pineal gland releases melatonin into the bloodstream. The added melatonin in supplements mimics this natural rise, reinforcing the body’s signal that it is time to rest. This gentle cue can make it easier to drift off to sleep without the stimulating effects that some prescription sleep aids have. The effect is usually felt within an hour of taking the product, though the exact timing depends on the formulation (immediate-release vs. extended-release).
Most people experience only mild, short-lasting effects, such as:
These symptoms typically resolve without medical intervention.
Rarely, melatonin can cause more serious issues that need urgent attention, including:
If any of these signs appear, seek medical help immediately.
People with the following conditions should use melatonin carefully and discuss it with a healthcare professional:
Pregnant or breastfeeding individuals are generally advised to avoid melatonin unless specifically recommended by a qualified practitioner.
Melatonin may interact with certain other medicines or substances:
Lifestyle factors such as driving, operating machinery or consuming caffeine close to bedtime should also be considered. For a full list of possible interactions, refer to the product-specific information leaflets for Meloset, Sleepose or Restfine.
Store melatonin products in a cool, dry place away from direct sunlight. Most formulations are intended for short-term use, but some individuals may take them for longer periods under professional guidance. Remember that each brand may have different release characteristics and strengths, so always follow the instructions that come with your specific product. For detailed usage, dosing and administration, refer to your medication’s own information.
Chronobiotic: A substance that helps adjust the body’s internal clock.
Extended-release: A formulation that releases the active ingredient slowly over several hours.
Sublingual: Placed under the tongue, where it dissolves and is absorbed directly into the bloodstream.
This article offers general educational information about melatonin as an active substance used in various medicines. Its purpose is to help patients better understand the ingredient and the conditions it is used to treat. It is not a substitute for professional medical advice or for the specific instructions provided with individual products. Medicines containing melatonin may differ in formulation, strength, and directions for use. Always consult the labeling of your particular medication and follow your healthcare provider’s guidance for complete information on proper use, dosage, and safety.
