Narcolepsy, sleep apnea, and shift work sleep disorder are disorders characterized by excessive daytime sleepiness; modafinil improves alertness and decreases this drowsiness by influencing neurotransmitters in the brain. Modvigil accomplishes its central nervous system stimulation—by aiming at orexin and other neurotransmitters—without the side effects of conventional stimulants. As a result, people are able to maintain more alertness and concentration throughout the day. For people who need to be extra alert during the day because of sleep disorders or unpredictable work schedules, Modvigil is a great option because it works and has few adverse effects.