How Long Does Melatonin Last in Your Body? Melatonin is fast-acting, with a half-life of 20 to 40 minutes. The half-life of a medication or supplement measures how long it takes for half the dose to be processed and eliminated by the body.

How long does melatonin take to wear off?

Melatonin takes between four to eight hours to wear off, but the amount of melatonin you take can cause this number to vary significantly. Generally, Buenaver suggests taking the lowest dose possible and advises starting at around one to three milligrams.

How long is it safe to take melatonin for sleep?

If melatonin does seem to help, it's safe for most people to take nightly for one to two months. “After that, stop and see how your sleep is,” he suggests.