Modafinil 100mg is frequently prescribed as a more conservative starting dose for patients who require wakefulness support but may be sensitive to the effects of stimulants. While the standard adult dose for narcolepsy and obstructive sleep apnea is 200mg, the 100mg tablet is the recommended primary dose for elderly patients or those with severe liver impairment, as these individuals metabolize the drug more slowly. In clinical settings, the 100mg strength is also used for dose titration, allowing doctors to gradually increase the medication to minimize side effects like headaches, jitters, or heart palpitations. Though it provides significant improvement in mental alertness compared to a placebo, studies suggest that 100mg may be less effective than higher doses for maintaining performance during periods of total sleep deprivation.