Rather, lack of. Melatonin is over-the-counter, generic, badly understood by the people taking it and dosed according to personal preference which means marketing it is all abouy big numbers. Bigger number on package = more sales.

They’re considered dietary supplements and not medicine, so they’re not meaningfully regulated in the way meds are.

> why is that

Why buy 1mg pill when you can buy 100mg pill?

Even funnier is that often 0.25mg or 0.5mg is closer to the correct dose, and those sizes tend to be hard to find.

There actually is a condition that calls for extremely high (100mg+ doses), but it is a very rare thing, no one should ever consider that much without instruction from a doctor. But you'll find it right next to the normal <=5mg doses without any explanation.

The Natrol liquid isn't usually too hard to track down. They advertise it as 1 mg or 2.5 mg, but it's the same stuff, the bottle just direct you to take 4 or 10 mL respectively.

So 1ml (20 drops) would yeild an average dose of .25mg in that form.

The help aiding sleep is only one function for melatonin. The reason for higher suggested doses is due to its anti-oxident function. From personal experience melatonin needs to be paired with vitamin e to really clear out over night. I take vitamin e as I get into bed right before I take a melatonin sublingual. Another benefit of melatonin is that it upregulates our insulin receptors.