can it be given through supplements?
Melatonin is categorized by the US Food and Drug Administration (FDA) as a dietary supplement.
Dietary supplement
Melatonin is categorized by the US Food and Drug Administration (FDA) as a dietary supplement, and is sold over-the-counter in both the US and Canada. FDA regulations applying to 
the primary high energy molecule in human metabolism is Adenosine triphosphate (ATP) what is catabolism? It is the set of metabolic processes that breaks down large molecules. which hormones are related to it? Cortisol, glucagon, adrenaline, cytokines, orexin and melatonin. what is the emotional response due to the third one? Fear. how does the first hormone related to metabolism of glucose? Cortisol stimulates the synthesis of 'new' glucose from non-carbohydrate sources; this is known as gluconeogenesis.. is process resisted by insulin? Yes. when was this substance which resists the process discovered? 1921. can it be extracted? Yes. from where? Pancreas. can we find in plants the last hormone in the list of hormones mentioned above? Yes. is it responsible for any memory related disease? No. how does it affect immune system? An antiinflammatory effect seems to be the most relevant. is it also found in animals? Yes. what is its function in animals? Seasonal functions such as reproduction, behavior, coat growth, and camouflage coloring.
Yes Yes, as a dietary supplement Yes
Melatonin Melatonin Melatonin
Dietary supplement Dietary supplement Dietary supplement
Melatonin is categorized by the US Food and Drug Administration (FDA) as a dietary supplement, and is sold over-the-counter in both the US and Canada. Melatonin is categorized by the US Food and Drug Administration (FDA) as a dietary supplement, Melatonin is categorized by the US Food and Drug Administration (FDA) as a dietary supplement, and is sold over-the-counter in both the US and Canada. 
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Melatonin [SEP] Dietary supplement
Melatonin is categorized by the US Food and Drug Administration (FDA) as a dietary supplement, and is sold over-the-counter in both the US and Canada. FDA regulations applying to medications are not applicable to melatonin, though the FDA has found false claims that it cures cancer. As melatonin may cause harm in combination with certain medications or in the case of certain disorders, a doctor or pharmacist should be consulted before making a decision to take melatonin. In many countries, melatonin is recognized as a neurohormone and it cannot be sold over-the-counter.