Modalert 100mg, also known as Modafinil, is primarily used to treat excessive daytime sleepiness associated with narcolepsy, obstructive sleep apnea, and shift work sleep disorder. It is not typically used to treat sleep disorders in the general sense, such as insomnia. Modalert works by promoting wakefulness and improving cognitive function rather than addressing the root causes of sleep disorders. It is important to consult with a healthcare provider before using Modalert to determine the appropriate treatment for any sleep-related issues.