In short
Melatonin is the hormone of darkness: a timing signal the brain releases at night, not a sedative. Used as a supplement it can shift the body clock, which is why it carries two authorised EU claims, for jet lag at 0.5 mg and for time to fall asleep at 1 mg. For ongoing insomnia the meta-analytic benefit is about seven minutes of faster onset. Retail products commonly carry ten to thirty times the physiological dose, and independent testing has found actual content ranging from a fifth to nearly five times the label. It is not in LAYER ZERO because it is a timing tool, not a nightly baseline, and because its regulatory status as a hormone varies across EU states. This page grades it the same way we grade our own ingredients.
This is the first page in the Library about something we do not sell. The test of an honest knowledge base is whether the grading stays the same when the ingredient is not ours.
01What melatonin is
Melatonin is a hormone the pineal gland releases when darkness falls, and its job is information, not sedation: it tells every clock-bearing tissue in the body that biological night has begun. The research literature classifies it as a chronobiotic, an agent that shifts the timing of the circadian system.1 That distinction runs through everything else on this page. A sedative pushes you toward sleep; a signal tells your clock when sleep belongs.
02Where it genuinely works
Used as a timing signal, melatonin has real evidence. A Cochrane review found it remarkably effective for jet lag when crossing five or more time zones, with 0.5 mg working about as well as 5 mg.2 Reviews of its clinical uses find the strongest support for reducing sleep onset in insomnia and for advancing the clock in delayed sleep phase syndrome.3 The EU register reflects exactly this shape: an authorised claim for alleviating subjective jet lag at a minimum of 0.5 mg, and one for reducing time to fall asleep at 1 mg.4 By the standards of this category, two authorised claims is rare and worth stating plainly. Context matters: melatonin was assessed under the standard procedure, while most botanical claims, including for ingredients in this system, sit in the EU's pending file, unassessed rather than rejected, as the claims page explains.
03Where it is oversold
The nightly-sleeping-pill use is where the numbers deflate. Across nineteen randomised trials in primary sleep disorders, melatonin shortened sleep onset by about seven minutes and added about eight minutes of total sleep.5 Real, measurable, and modest; a warm shower an hour before bed produces a comparable onset effect. For the chronic can't-switch-off insomnia most people are actually medicating, the problem is usually arousal, covered in wired but tired, and a darkness signal does not treat arousal.
04The dose inflation
Physiological night-time melatonin corresponds to a dose around 0.3 mg; in a controlled trial in older adults, 0.3 mg restored sleep efficiency while 3 mg pushed daytime levels above normal.6 Retail products of 5 and 10 mg are ten to thirty times the physiological signal, with no evidence the excess helps and some that it lingers into the day. With hormones, more is not a stronger version of the same instruction. It is a different instruction.
05The label problem
Independent testing of 31 melatonin supplements found actual content ranging from 17 percent to 478 percent of the label, with lot-to-lot swings up to 465 percent, and serotonin present in a quarter of them.7 For a hormone whose sensible dose is a fraction of a milligram, that variance is not a quality footnote; it is the difference between a signal and a flood. It is also the strongest argument for treating melatonin as the regulated substance it increasingly is: several EU states class it as medicinal above low thresholds, and its status varies country to country.
06Why it is not in this system
The honest reasoning
Melatonin is a good tool we deliberately left out. LAYER THREE is built for every night, and a hormone is not a nightly baseline: the strong use cases are episodic, shifting a clock across time zones or advancing a delayed one. Its regulatory status as a food ingredient is unsettled across the EU markets this system ships to. And the formulation's evening logic is support for the body's own downshift rather than adding a hormone from outside. When a trip justifies it, the travel protocol says so openly. That is what not underselling and not overselling looks like from the other side of the counter.
In the system
The physiology melatonin signals into is in why recovery starts before bed and the circadian day. The evening layer's own ingredients are graded in the Ingredient Library. Build your protocol →
Sources
Next in this thread
Why recovery starts before bedThe downshift melatonin signals into, and the levers that belong to you.→How we handle evidence. This page grades a substance we do not sell by the same standard as the ones we do, including the claims it holds and ours do not. Educational content, not medical advice.