The main purpose of modafinil is to encourage alertness in those who suffer from excessive daytime drowsiness. Its primary recognized applications include the treatment of narcolepsy, shift work sleep disorder, and drowsiness related to obstructive sleep apnea (in conjunction with other medications). Modafinil helps users stay awake and attentive by affecting brain chemicals related to alertness and the sleep-wake cycle. Additionally, some people use it off-label to increase focus and mental clarity; however, this should be done carefully and under a doctor's supervision. For these uses, modafinil is frequently given under the name Modvigil 200, which has 200 milligrams of the active ingredient.