Melatonin-Nebenwirkungen: was die Evidenz zeigt

Melatonin is the hormone the pineal gland releases in darkness to tell the body it is night; supplemental melatonin mimics that signal rather than sedating the brain the way a sleeping pill does. Because it is a low-dose hormonal signal, not a drug that suppresses the nervous system, its side-effect profile is mild compared with hypnotics: reviews find short-term use produces adverse events at rates close to placebo (Buscemi et al. 2006). The effects that do occur follow directly from its biology: it tells the body it is night, so the dominant complaint is feeling like it is still night the next morning.

The most consistently reported effects across trials are daytime sleepiness or morning grogginess, headache, dizziness, and unusually vivid dreams (Besag et al. 2019). They are usually mild and short-lived, and most are dose-dependent, meaning they get more likely as the dose climbs. Vivid or strange dreams likely reflect melatonin's influence on sleep timing and REM distribution rather than any danger. None of these are reasons to fear melatonin at a sensible dose, but they are reasons to start low: most of the discomfort people blame on 'melatonin' is really the discomfort of taking far more than the body ever produces at night.

Physiological night-time melatonin levels are tiny, and a dose of about 0.3 mg already restores them; Zhdanova et al. 2001 showed this low dose is as effective as much larger ones for sleep, with higher doses adding no benefit. Common retail products contain 3, 5, or even 10 mg, pushing blood levels many times above anything the body makes, which keeps melatonin elevated into the morning and is the main driver of next-day grogginess. Higher is not stronger for sleep; it is mostly stronger for side effects. The dosing logic and why less is more is covered in detail in the melatonin dosing guide.

Melatonin does not act on the receptors that drive dependence with benzodiazepines or z-drugs, and reviews have not found the tolerance or withdrawal pattern seen with sedative hypnotics. The 'melatonin hangover' people describe is the grogginess of a high dose still circulating in the morning, not a withdrawal effect, and it resolves by lowering the dose or shifting the timing earlier. That said, relying on it every night can become a psychological habit and can mask an untreated sleep problem, so it is better used as a short-term timing tool than as an indefinite nightly crutch.

Melatonin can interact with anticoagulants (blood thinners), immunosuppressants, some diabetes medications, and other sedatives, so anyone on these should check with a clinician before use. It is generally not recommended during pregnancy or breastfeeding, or for children, without medical supervision, because long-term safety data in these groups is limited. People with autoimmune conditions or epilepsy, and anyone whose daytime alertness matters for safety (driving, machinery) if grogginess appears, should also be careful. Because supplement labels are frequently inaccurate about actual content, buying from a reputable brand matters more here than with most supplements.

If you are taking melatonin nightly for chronic insomnia and it is barely helping, the issue is usually that melatonin is the wrong tool: it shifts the timing of the clock and is most useful for a delayed rhythm or jet lag, not as a sedative for staying asleep. The first-line treatment for chronic insomnia is behavioral (CBT-I), not a supplement. For understanding what melatonin does and does not do mechanistically, see the guide on what melatonin actually does, and for persistent waking in the night see the stay-asleep protocol. This article is educational and not medical advice; discuss ongoing sleep problems and any medication interactions with a doctor.