While dosage guidelines have not been established for melatonin, information about dosing can be obtained from clinical trials and practical experience with the supplement. Doses ranging from 0.3 to 5 mg once daily seem to work well. Since there is not enough evidence to recommend a standard dose of melatonin, you should start with a reasonable dose and see how you react to it.
It is important to note that unlike medications (for which the standard doses have been well established), less information is available for determining the best dose for supplements, including melatonin.
What Is a Reasonable Dose of Melatonin?
Some information about melatonin dosing can be obtained from clinical studies and from practical experience with the supplement. For most uses, doses ranging from 0.3 to 5 mg once daily (usually in the evening) seem to work well. You may find it best to try melatonin at bedtime first. If you find that the supplement does not work quickly enough for you, you may try taking it earlier in the evening.
Like many treatments for sleep disorders, you may not need to take melatonin on a long-term basis. You may only need a few weeks of treatment (or even less) in order to get your sleep cycle back on track. Even if you are not taking the supplement for sleep, it is probably best to take it in the evening, as taking it during the day can cause daytime drowsiness and decreased alertness.
Since there is not enough strong evidence to guide you in your choice of a dosage, a good plan is to start with a reasonable dose and see how your body reacts to it. If you find that you are groggy in the morning and have trouble getting up, or if you are experiencing other melatonin side effects, a lower dose might be better. If it seems to be working a little but not quite well enough, a higher dose might be right for you. A maximum safe melatonin dose has not been established.