A nasal spray containing a naturally occurring brain hormone called orexin A reversed the effects of sleep deprivation in monkeys, allowing them to perform like well-rested monkeys on cognitive tests. The discovery's first application will probably be in treatment of the severe sleep disorder narcolepsy.
I haven't known anyone who has narcolepsy - but it is a serious ailment. They can fall asleep while driving, just zonk out anywhere...and that could easily hurt others around them.

One example of something else: People with ADD or ADHD (and scans have shown these types of brains to definitely be 'wired' differently) often have a history of alcohol or other abuse.

So, research on brain chemistry will hopefully continue to provide long-term solutions for those who 'self-medicate'.