Melatonin

The signal your brain uses to tell the time. A small dose at the right time moves your body clock. For ordinary sleeplessness it gets you to sleep about 7 minutes sooner.

At a glance

Our verdict	A body-clock signal, not a sleeping pill: for a late body clock, jet lag, and prolonged-release 2 mg at 55+. Not for ordinary insomnia under 55.
Best use	Body clock: jet lag, shift work, a late body clock
How sure the evidence is	Moderate for a late body clock
Cost a month	About $1.50 to $3

Written for adults in Canada. It explains the evidence; it is not advice for you personally. Last reviewed 20 October 2026.

Supplement Check

Is it right for you?

Melatonin helps only some sleep problems, and the timing matters more than the dose. Your check asks when you fall asleep, whether you travel or work nights, screens for sleep apnoea and checks your medicines first. Our Supplement Check looks at:

Pregnancy, planning a pregnancy, or breastfeeding: every Canadian melatonin licence read says not to use it
Possible sleep apnoea: loud snoring, pauses in breathing seen by a partner, daytime sleepiness, higher weight or high blood pressure
Epilepsy or a past seizure
An autoimmune condition, or a medicine that dampens the immune system
Taking fluvoxamine or warfarin
Every medicine you take

Coming soon. The Supplement Check and the Online Health Assessment open once our safety testing is complete.

$59 when it opens, paid once. Adults 18 and over, anywhere in Canada. While the service is new, Dr. French reads every report himself, and your report arrives within 3 working days. More about the Supplement Check

Tell me when it opens

What it is

Melatonin is the hormone the pineal gland releases in darkness, starting about 2 hours before your usual sleep time. In Canada it is sold as a licensed natural health product from 0.1 to 10 mg; of 834 active licences, only 53 are 1 mg and 4 are 0.5 mg, while most are 3, 5 or 10 mg. [1]

Prolonged-release 2 mg (Circadin) is the product tested in older adults. Canadian timed-release 2 mg products exist but have not themselves been tested in trials.

Which product. A single-ingredient 1 mg tablet (half a tablet gives 0.5 mg). We have not yet named a brand: no Canadian maker publishes batch melatonin results, and we are asking for a certificate of analysis first. Gummies and combinations (with 5-HTP, L-theanine or herbs) are not used.

Structure of Melatonin — Structure: PubChem (public domain).

How it acts

Melatonin acts on receptors in the brain's master clock. It has two separate effects.

It moves the clock. Taken in the afternoon or early evening it moves the clock earlier; taken early in the morning it moves it later; taken at bedtime it barely moves it at all. At its best time, 3 mg moved the clock up to about 1.8 hours earlier over 3 days, [2] and 0.5 mg, taken at its own best time, moved it by a similar amount. [3] In people with a late clock, the earlier the dose was taken relative to their own melatonin rise, the larger the shift. [4]
A mild sleep-promoting effect, mainly when your own melatonin is low. It is not a sedative like a sleeping pill. [5]

That is why the timing matters more than the dose.

Outline of a person showing where Melatonin acts in the body

What it is used for, and what the evidence says

Use	What the trials found	How sure we are
Late body clock (delayed sleep–wake phase)	116 adults, 4 weeks: 0.5 mg 1 hour before the desired bedtime, plus a fixed sleep schedule, against placebo with the same schedule. Falling asleep 34 minutes earlier (somewhere between 8 and 60 minutes); 52.8% against 24.0% rated improved by a clinician; side effects similar to placebo. [6] The American Academy of Sleep Medicine endorses timed melatonin for this. [7]	Moderate
Jet lag, 5 or more time zones	A Cochrane review of 10 small trials: 9 found that melatonin at destination bedtime reduced jet lag. For every 2 people who take it, one benefits. 0.5 to 5 mg worked similarly; more than 5 mg was no better; the benefit was greater flying east. Taken early in the day it causes sleepiness and delays adapting. [8]	Low to Moderate
Shift work: sleeping in the day after a night shift	9 trials, 1 to 10 mg after the shift: 24 minutes more daytime sleep, but no faster falling asleep, and no difference by dose. [9]	Low
Insomnia at 55 and over, prolonged-release 2 mg	354 people aged 55 to 80, 3 weeks: better sleep quality and morning alertness in 26% against 15%; falling asleep 24 minutes faster against 13 on placebo. [10] Over 6 months: 19 minutes faster against 2, no loss of effect, side effects similar to placebo. [11] Both trials were funded by the maker.	Low to Moderate
Ordinary insomnia	19 trials, 1,683 people: falling asleep 7 minutes faster and 8 minutes more sleep. [5] The American Academy of Sleep Medicine suggests not using it for chronic insomnia. [12]	Moderate (that the effect is small)
Dementia with disturbed sleep	The American Academy of Sleep Medicine recommends against it. [7]	Low (not recommended)

How sure we are: High means further research is very unlikely to change the answer; Moderate, it might; Low, it may well change; Very low, we are very unsure. These follow the GRADE method that guideline panels use.

Benefits

Late body clock: falling asleep about 34 minutes earlier, with a fixed schedule (moderate certainty).
Jet lag: 1 in 2 people helped (low to moderate certainty).
After a night shift: about 24 minutes more daytime sleep (low certainty).
Insomnia at 55 and over, prolonged-release 2 mg: falling asleep about 19 minutes faster than placebo (low to moderate).
Ordinary insomnia: about 7 minutes, which is too small to recommend.
Cheap: $1.50 to $3 a month.

Risks and side effects

Next-day drowsiness, headache, dizziness, vivid dreams, nausea. In the late-clock trial, light-headedness, daytime sleepiness and lower sex drive occurred at rates similar to placebo. [6]
Wrong time, wrong direction. Taken in the morning it moves the clock the wrong way and makes you sleepy. [8]
Blood sugar. In a 2026 crossover trial of 21 people, 5 mg worsened glucose handling by 11.7% and cut the first burst of insulin by 40% in carriers of a common diabetes-risk gene variant (about 30% of people of European ancestry). [13] Another reason to keep the dose at 0.5 to 1 mg and not take it with a late meal.
Labels you cannot trust. Canadian products tested contained from 83% less to 478% more melatonin than the label, varied up to 465% between batches of the same product, and 8 of 31 contained serotonin. [14]
Children. In the US, poison-centre reports of children swallowing melatonin rose 530% in 10 years; 5 needed a breathing machine and 2 died. [15] Keep it out of reach.

Interactions with medicines

Melatonin does not change how the liver clears other medicines. The reverse is the problem: it is cleared mainly by one liver enzyme (CYP1A2), and medicines that block that enzyme raise melatonin levels.

Medicine	What can happen	What to do
Fluvoxamine	Melatonin exposure 17 times higher [16]	Do not take; see a doctor
Warfarin	Case reports of a change in INR [8]	Held for a doctor
Transplant and other immune-suppressing medicines	Licence: consult first [1]	Held for a doctor
Sleeping pills, benzodiazepines, opioids, gabapentin, pregabalin, sedating antihistamines; alcohol	Added drowsiness [1]	Caution; start at 0.5 mg; no alcohol
Ciprofloxacin, enoxacin	Higher melatonin levels (enzyme blocked)	Caution while on the course
Oral oestrogen (the pill, hormone therapy)	Higher melatonin levels	Start at 0.5 mg
Seizure medicines, blood-pressure medicines, steroids	Licence: consult first [1]	Caution
Smoking	Speeds clearance; lower levels	No action

Who should not take it

Pregnancy, planning a pregnancy, or breastfeeding: every Canadian melatonin licence read says not to use it. [1]
Possible sleep apnoea: loud snoring, pauses in breathing seen by a partner, daytime sleepiness, higher weight or high blood pressure. Dr. French's rule: sleep apnoea is checked before any sleep product.
Epilepsy or a past seizure: a doctor first (no conclusion is possible from the trials). [17]
An autoimmune condition, or a medicine that dampens the immune system: a doctor first.
Taking fluvoxamine or warfarin.
Diabetes: caution; low dose, not with a late meal. Heart, liver or kidney disease, or asthma: the licence says consult. [1]
No driving or machinery for 5 hours after a dose (night-shift workers: take it only once home).
Insomnia lasting more than 4 weeks: see a doctor.
Dementia with disturbed sleep: not recommended.
Children: only with their doctor. Under 18: outside the Supplement Check.

Dose and timing

Late body clock: 0.5 to 1 mg, 3 to 5 hours before the time you now fall asleep (or, as in the trial, 1 hour before your desired bedtime with a fixed wake time). Move it 30 to 60 minutes earlier every few days as your sleep moves. 4 to 6 weeks, then review. [3, 6]
Jet lag, flying east across 5 or more time zones: 0.5 to 3 mg at local bedtime (10 pm to midnight) for the first 2 to 5 nights after arrival. Never in the morning. Flying west it is usually not needed.
Night shifts: 1 mg (up to 3 mg) just before your daytime sleep, only once you are home.
Insomnia at 55 and over: prolonged-release 2 mg, 1 to 2 hours before bed, for up to 3 months, if a sleep programme (cognitive behavioural therapy for insomnia) has not helped enough.
With every clock problem: the same wake time every day, outdoor daylight within an hour of waking, and dim light for the last 2 hours before bed. Melatonin helps these work; it does not replace them.
One product only. If you already take melatonin, replace it, never add.
How to tell it is working: a sleep diary or wearable for 2 weeks before and 4 weeks on. For a late clock, the aim is falling asleep within 30 minutes of your desired bedtime on most nights. No change after 4 weeks at the right time: stop and book.
Store at room temperature, dry and dark.

What we know about Canadians

About 1 in 6 Canadian adults (16.3%) had insomnia disorder in a 2023 national survey. In one year, 28.7% used natural or over-the-counter sleep aids, 15.6% cannabis, 14.7% prescribed sleeping pills and 9.7% alcohol. [18] Night-time insomnia symptoms affect 18 to 20% of adults and 24% of women aged 18 to 64. [19]

Sleep apnoea is the problem often missed: among Canadians aged 45 to 85, 28.1% were at high risk of moderate-to-severe sleep apnoea (27.5% in New Brunswick), and about 93% of them had not been diagnosed. [20] That is why we screen before any sleep product.

Most at risk of insomnia: women, Indigenous people, people in poorer mental or physical health; older adults (more prescribed pills) and young adults (more cannabis, alcohol and over-the-counter products).

How sure are we: moderate. National surveys with standard criteria, but self-reported; sleep apnoea risk is from a screening questionnaire, not sleep studies.

An honest comparison: sleep and the body clock

Effects against placebo where trials report them, with the cost a month in Canadian dollars. No medicine is approved to move the body clock; sleeping pills treat sleeplessness, not timing.

Option	Effect	How sure we are	Cost a month (CAD)
Melatonin 0.5 mg, late body clock	34 minutes earlier to sleep, on top of the schedule [6]	Moderate	$1.50 to $3
Melatonin, prolonged-release 2 mg, age 55 and over	About 19 minutes faster to sleep against 2 on placebo [11]	Low to Moderate	$3 to $5
Melatonin, ordinary insomnia	7 minutes faster to sleep [5]	Moderate (small)	$1.50 to $3
Cognitive behavioural therapy for insomnia (app, programme or therapist)	19 minutes faster to sleep, 26 minutes less awake in the night; lasts after treatment ends [21]	Moderate to High	Free (app) to about $90 (therapist)
Fixed wake time, morning daylight, dim evenings	The schedule both groups followed in the late-clock trial; not measured on its own [6]	Not graded	Free
Sleeping pill (zopiclone in Canada)	22 minutes faster to sleep while taken; [22] over 60, about 5 times the rate of memory and thinking side effects; [23] no help to day sleep after night shifts [9]	Moderate	$8 to $12

Read honestly: for a late body clock, low-dose melatonin at the right time is the best option we have, cheap and safe. For ordinary insomnia it does almost nothing; a sleep programme works better and keeps working after you stop.

Our verdict

For adults with a late body clock (unable to fall asleep before 1 or 2 in the morning and struggling to wake): 0.5 to 1 mg, timed, with a fixed wake time and morning light. For jet lag flying east across 5 or more time zones: 0.5 to 3 mg at local bedtime. After night shifts: 1 mg before daytime sleep. At 55 and over with insomnia that a sleep programme has not fixed: prolonged-release 2 mg for up to 3 months.

Not for ordinary insomnia under 55, not in pregnancy or breastfeeding, not with fluvoxamine, and not before sleep apnoea has been considered.

Melatonin is a timing signal, not a sedative. Taken at the right time, a small dose moves the body clock about as much as a large one, with fewer side effects, and for a late clock no medicine does the job. For ordinary sleeplessness it saves about 7 minutes, and a sleep programme works better and lasts. Dr. French approved melatonin for these uses at these doses (0.5 to 1 mg for the body clock, 0.5 to 3 mg for jet lag, 2 mg prolonged-release at 55 and over) and not for ordinary insomnia. Because almost 3 in 10 Canadians over 45 are at high risk of sleep apnoea and most do not know it, his rule is that apnoea is checked before any sleep product. And because Canadian labels are unreliable, we name a brand only once its maker has shown us a batch test.