What is melatonin: dosage and side effects?

Melatonin is a naturally occurring hormone in the body that helps to regulate our sleep patterns. As we sleep, our levels of melatonin rise and as we wake the levels go back down to normal. Based on this knowledge, we can help treat sleeping problems by increasing or supplementing levels of melatonin natural hormone before bedtime using synthetic melatonin taken as a tablet/liquid. Melatonin is usually a well tolerated medication with very little side effects for most people. Let’s get into some frequently asked questions.

What Is Melatonin and How Does It Work?

So what is melatonin and how does it really work? You may have heard of people taking melatonin for sleep, this is the synthetic version of melatonin that is taken orally. Melatonin itself is a natural hormone in the body that helps to manage your sleep cycle (how long you sleep, when you sleep etc.); to do this, the levels of the hormone naturally go up and down. The natural pattern is higher melatonin levels at night and then lower during the daytime.

Therefore, one way you can treat sleeping problems is by taking synthetic melatonin. The increase in melatonin tells your body that it is time to sleep. This can help you get to sleep more easily and stay asleep through the night. Melatonin supplements are often taken as a tablet or capsule but it can also come as a liquid. So how long does melatonin take to work? Usually around 1-2 hours so it is very effective.

Who Commonly Uses Melatonin Supplements?

Melatonin supplements are typically used to help manage problems with sleeping such as a sleep medications from insomnia. It can also be used for long-term sleep problems or short-term ones. Some examples of cases where melatonin sleep aid may be used include jet lag, Chronic Fatigue Syndrome, Cerebral Palsy, and Attention Deficit Hyperactivity Disorder (ADHD). Melatonin is suitable for most adults but children should seek medical guidance before taking it.

Recommended Melatonin Dosage by Age and Purpose

The recommended Melatonin dosage can vary depending on your age and what problem you are taking the medication for. Here is a tablet outlining some common cases but please consult a doctor if you are unsure.

How to Take Melatonin Safely

So is melatonin safe? Generally, yes. To take melatonin safely, here is some general advice:

• You should take melatonin with food. Swallow the melatonin tablet/capsule whole with water and do not bite it.
• Make sure you stick to your doctor’s instructions or the guide on the medication packet.
• Do not take more tablets than needed and do not take the supplements for a longer time than recommended/needed.
• You should try to avoid alcohol because it can make you very drowsy.
• You should try to avoid caffeinated drinks (e.g tea, coffee) because it can decrease the effect of alcohol.
• Try to avoid recreational drugs (e.g cannabis, cocaine) which can interact with melatonin and cause side effects.
• You should buy Melatonin from a reputable source such as Meds for Less

Check with a healthcare professional if you are still unsure about taking melatonin or you have other specific questions.

Potential Side Effects and Risks

Melatonin is usually well tolerated and does not cause many side effects. However, it is still important to be aware of some possible side effects and risks so that you can seek advice from a healthcare professional or emergency medical attention where needed.

Common melatonin side effects:

• drowsiness
• headache
• nausea
• dry mouth

If these common side effects persist, please consult a doctor.

Severe side effects (call 111 or seek medical attention):

• vision changes (e.g becoming blurry)
• fainting
• confusion and dizziness
• bleeding (e.g in pee, bruising, cut that does not stop bleeding)
• serious allergic reaction (e.g feeling like you cannot breathe/swallow, swollen tongue/mouth/throat, sudden confusion, fainting etc.) – in this case call 999

Interactions with Medications and Other Supplements

If you are taking any other medications or supplements, please consult a doctor before starting melatonin. This is because many medications and supplements can affect melatonin (or the other way around) and it can lead to side effects. For example, some medications can increase the effect of melatonin and may make you extremely drowsy.

Some common medications/supplements that interact with melatonin include:

• ibuprofen and other non-steroidal anti-inflammatory drugs
• oestrogens in the combined contraceptive pill or hormone replacement therapy
• carbamazepine
• warfarin
• diazepam

When to Avoid Melatonin Use

Please consult a doctor before taking melatonin if you have any medical condition. Some conditions where this is the case include:

• kidney conditions
• liver conditions
• autoimmune conditions e.g multiple sclerosis, systemic lupus erythematosus

How Melatonin Works Within the Sleep–Wake Cycle

A clear understanding of how does melatonin work provides insight into why it is widely used to support healthy sleep. Melatonin is not a sedative; instead, it acts as a signalling molecule that communicates to the brain that it is time to prepare for rest. Its release follows the body’s circadian rhythm, which responds to changes in natural light and darkness.

Key steps in the melatonin pathway:

• Light decreases in the evening, triggering the pineal gland to begin releasing melatonin.
• Melatonin levels rise in the bloodstream, promoting a gradual reduction in alertness.
• Core body temperature begins to fall, helping the body transition into a restful state.
• Receptors in the brain respond to melatonin, supporting the timing of sleep onset and stabilising the sleep–wake cycle.
• Levels naturally decrease in the morning, allowing the brain and body to return to a wakeful, alert state.

Why melatonin supports sleep regulation

• It reinforces the circadian rhythm, making sleep onset more predictable.
• It helps synchronise internal processes with external cues, such as daylight or darkness.
• It is particularly helpful when natural patterns are disrupted by shift work, jet lag or inconsistent sleep habits.
• Because it functions as a timing cue, melatonin for sleep works best when taken at the same time each evening.

By guiding the body’s internal clock rather than inducing sleep directly, melatonin creates the conditions for a smoother, more natural transition into rest.

How Long Does Melatonin Take to Work?

The question of how long does melatonin take to work depends on the formulation. Most oral forms begin to take effect within 30 minutes to two hours, allowing users to fall asleep more easily and maintain stable sleep cycles.

Immediate-release products tend to provide quicker effects, while prolonged-release forms imitate the body’s natural overnight melatonin pattern, supporting sleep maintenance rather than only sleep onset.

Additional Therapeutic Uses of Melatonin

Although sleep regulation is the most recognised purpose, melatonin uses extend to several other clinical and non-clinical situations. It may support individuals experiencing circadian rhythm displacement (such as shift workers), neurological conditions that affect sleep cycles, or developmental disorders where sleep patterns are frequently disrupted.

In such contexts, melatonin may act as a melatonin sleep aid to stabilise timing and enhance overall sleep quality. As with any supplement, usage should be tailored to the individual’s condition and response.

Tips for Improving Sleep Without Supplements

If you are unsure about melatonin or you want to make some changes to improve your sleep to support the function of melatonin, there are many ‘sleep hygiene’ tips you can try:

• Try to sleep and wake up at similar times every day. Keeping a regular pattern helps your body’s sleep cycle.
• Avoid taking long naps during the day and try to only use your bed for relaxing activities like sleeping (i.e not working in bed).
• Try not to use your phone (or use any screens) 1-2 hours before bedtime. Reading, taking a bath, journaling, or listening to calming music are some examples of other off-screen activities you can do to relax before bed.
• Make your sleep environment more comfortable (quiet and cool). You could use blackout curtains or change pillows.
• Take care of your overall health. Eat well and get regular exercise. Try to avoid caffeine in the afternoon and evening.

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