The amount of pseudoscience on this topic is staggering, and there's seemingly almost no thought given to adverse effects. Incidentally, a good rule of thumb is

The amount of pseudoscience on this topic is staggering, and there's seemingly almost no thought given to adverse effects. Incidentally, a good rule of thumb is that anyone who claims that their preferred intervention (for anything, not just productivity/engagement) is beneficial and has "no side effects" or "only good side effects" is very nearly 100% likely to be full of shit. The only way to have no risk of adverse effects is to have no effects at all.