Melatonin

Key facts

• Melatonin is a hormone your body makes naturally to signal nighttime; as a tablet or capsule it is used short-term for insomnia and for circadian problems such as jet lag or shift-work sleep issues.
• Take it 30 to 60 minutes before your intended bedtime; effects are milder than prescription sleeping tablets, and it works best alongside consistent sleep habits.
• It can cause drowsiness the next day, so treat it as a real medicine rather than a harmless extra, and don't drive until you know how it affects you.
• It interacts with some medicines, including blood thinners, anticonvulsants, immunosuppressants, and diabetes medicines; tell your prescriber or pharmacist you are taking it.

What melatonin treats

Melatonin is used for short-term insomnia (trouble falling asleep), jet lag, delayed sleep phase (feeling sleepy very late and waking late), and sleep disruption from shift work. It is not a treatment for long-standing, chronic insomnia, and it does not treat anxiety or depression.

How melatonin works

Your brain releases melatonin from the pineal gland in the evening as darkness falls, signalling to your internal clock that it is time to prepare for sleep. Taking melatonin as a tablet reinforces or shifts that signal, helping you fall asleep at the intended time rather than sedating the brain directly the way sleeping tablets do.

Before you take it

• Talk to a doctor before giving melatonin to children, or taking it if you are pregnant or breastfeeding; evidence in these groups is limited.
• Tell your prescriber if you have an autoimmune condition, epilepsy, or depression, and about any blood thinners, anticonvulsants, immunosuppressants, diabetes medicines, or hormonal contraceptives you take; melatonin can change how these work.
• Avoid combining it with alcohol or other sedating medicines, which can deepen drowsiness.
• Buy from a reputable source: studies have found the actual melatonin content of some products varies widely from the labelled dose.

Side effects

Common effects include daytime drowsiness, headache, dizziness, stomach upset, and vivid dreams.

Stop and seek urgent medical care for any of these:

• Severe allergic reaction: rash, facial or throat swelling, difficulty breathing.
• Marked daytime sedation that affects driving or coordination.
• New mood changes, or a fast or irregular heartbeat.

Safety essentials

• Melatonin is intended for short-term use, a few weeks at most. If sleep problems continue beyond that, see a doctor rather than continuing indefinitely on your own.
• Because it can cause daytime drowsiness, don't drive or operate machinery until you know how it affects you the next morning.
• Tell every prescriber and pharmacist you take melatonin, since it can raise or lower the effect of blood thinners, seizure medicines, immunosuppressants, and diabetes medicines.
• Take it at a consistent time relative to your intended sleep, not randomly during the day, since timing is central to how it works.

This page is educational and does not replace advice from a doctor or pharmacist who knows your health history.