[QUOTE=JenniLeigh;60032]Amaroli is primarily useful for it’s melatonin content, which is unnecessary and urine does contain toxins. It is basically, for someone who enjoys this idea, rather than for scientific purposes. If one cannot remain meditative without the use of additional melatonin, I would question the relevance of their meditative state, since it is temporary and dependent upon external forces.[/QUOTE]
Well, anyone is dependant upon externalities to a certain extent. If we follow this logic eating shouldn’t be allowed too, why eat when you can hold prana with siddhic power?
But not anyone is fully developed, and if they were fully developed they wouldn’t be practicing yoga, I guess. 
So I see no problem with someone utilizing something external for a deeper internal purpose.