Since someone brought up marketing ..
Marketing tries to create a felt need ... by listing all the bodily processes that utilize a particular substance and by listing common symptoms you may be experiencing ( that could have a myriad causes ). They can't tell you if you are deficient or unable to properly absorb a particular supplement ... i.e. they can't confirm you HAVE A NEED OR that their formula is best for you.
There is a ton of market hype and scams - like organic food, essential oils, cleansing/purging toxins, etc. I ignore the BS. And focus on brain supplements - I find they typically do just what they claim to do. For instance, Magtein (magnesium threonate) claims it's the best form of magnesium to penetrate the brain. I can confirm this as I can feel it kick in. It's not even ambiguous, it's definite. Taurine is a calming neuroprectant and may bind with GABA receptors. I can attest to the calming and it does feel soothing to my inflamed nerves. I'd recommend it for sleeping - maybe blended with a bit of DMAE (acetylcholinergic).
There's not much marketing behind Dopa Mucuna AFAIK. I just tried it because it's cheap and readily available. Only real dopamine solution. And it definitely supplies some neurotransmiiter I haven't found in any other supplement - even tyrosine (which is supposed to affect dopamine). Kind of euphoria for me.