Modafinil is a stimulant drug used to reduce the sleepiness that you may experience if you suffer from Narcolepsy. It can increase your ability to stay awake by nearly 50% as it stimulates the central nervous system. As it is a developed drug it holds less likelihood that you will become addicted to the drug and withdrawals are generally not suffered if you are taken off the drug correctly. It is sometimes the case that Modafinil is not strong enough and it can be used with other stimulants in these cases. A common side-effect of this drug is headaches, and should you suffer repeatedly from headaches since taking the drug then medical advice should be sought.