There was a number of studies done to get a better understanding of what exactly controls sleep mechanism in our brain, which would help us to better understand how sleep disorders develop and why. It is now been acknowledged that there are two mechanisms that are responsible for our wake/sleep cycle – one promotes sleep and the second one wakefulness.
Numerous studies dissecting the basic mechanisms that control sleep regulation have led to considerable improvement in our knowledge of sleep disorders. It is now well accepted that transitions between sleep and wakefulness are regulated by complex neurobiologic mechanisms, which, ultimately, can be delineated as oscillations between two opponent processes, one promoting sleep and the other promoting wakefulness.
Stimulants similar to amphetamines increase wakefulness by blocking or stimulating dopamine. Provigil possible works by interacting with hypocretin system