Core argument
Melatonin is a real circadian signal sold like a simple sleep aid, in a bottle the label cannot fully vouch for. This map separates what the hormone does from what the supplement promises, so you can judge the product, not the packaging.
Counter-intuitive point
The surprise is not that melatonin sometimes helps. It is that timing matters more than milligrams, and the least reliable part of the story may be the label itself. See the 'Myths debunked' branch in the outline for the full reversal.
What to do next
Work through the decision checklist branch before buying: start low, verify the product, and know when to stop and ask a clinician.
Connections
A companion to 'Sleep Better: An Evidence-Based Playbook' and 'Social Jetlag: Your Weekend Is the Disease', carrying the sleep series from tuning and rhythm into the supplement controversy.
The Melatonin Paradox: What's Actually in the Bottle, and What We Still Don't Know
First, what melatonin actually is
A darkness signal, not a sedative
Pineal gland releases it after dark
It shifts timing, not sleep pressure
Dim light at night delays release
Why timing beats dose
Same dose, wrong hour, weak effect
Morning light anchors the clock
It cannot override caffeine or screens
The bottle problem: label versus content
31 products tested, most missed label
71% deviated from label by over 10%
Range: minus 83% to plus 478%
26% hid unlisted serotonin
Erland and Saxon 2017, JCSM
Why labels can drift this far
DSHEA 1994: no pre-market approval
Shelf doses span 0.3 to 10 mg
Gummies vary most, batch to batch
Use in the US rose fivefold
0.4% of adults in 1999-2000
2.1% by 2017-2018, JAMA 2022
A fivefold rise in twenty years
What evidence actually supports
Jet lag: the strongest case
Cochrane review backs eastward travel
Works best across five or more zones
Use for a few days, then stop
Delayed sleep phase: modest help
Timed doses can shift bedtime earlier
Light therapy often pairs with it
Chronic insomnia: weak case
AASM 2017: weak recommendation against
CBT-I, not pills, is first-line care
Dose studied is small
Most trials used 0.5 to 5 mg
Higher doses show no added benefit
Myths debunked
Natural means safe: false
Hormone dose still alters physiology
Unlisted serotonin shows the gap
More milligrams, stronger sleep: false
Excess can cause morning grogginess
Vivid dreams and nausea reported
Nightly forever, no downside: unproven
Long-term trials are short and small
Stopping after short use is normal
Knocks you out like a pill: false
It nudges the clock; sleep still comes
Caffeine and light can override it
Risks people underestimate
Children: the sharpest rise
Poison-center calls up 530%, 2012-2021
Two deaths reported in CDC data
Gummies look and taste like candy
Interactions worth a pharmacist check
Blood thinners: bleeding risk reports
Diabetes drugs: blood sugar shifts
Immune suppressants and blood pressure drugs
Next-morning effects
Grogginess, headache, vivid dreams
Driving risk if dose taken too late
If you use it: a decision checklist
Start low, time it right
Begin at 0.5 to 1 mg
Take 1 to 2 hours before bedtime
Same time nightly for a few nights
Buy for verification, not marketing
Look for USP, NSF, or ConsumerLab seals
Prefer tablets over gummies for consistency
Check lot number and expiry date
If-then rules before you buy
If on regular medication, ask pharmacist first
If pregnant or breastfeeding, ask clinician first
No benefit in two weeks? Reassess
Store it like medicine
Locked cabinet, out of children's reach
Child swallows any? Call poison control
What we still do not know
Long-term safety is unmapped
No large multi-year trials in adults
Puberty and hormone effects unstudied
Children and teens: evidence thin
Short trials only, doses unstandardized
Guidelines stay cautious for adolescents
The dose question is open
No agreed optimal dose or timing protocol
Formulation differences barely studied
Regulation may change the story
Third-party testing is voluntary today
Future rules could force label accuracy