When Modafinil is prescribed for narcolepsy, the dosage is 200-400 mg per day, divided into two dosages, taken first thing in the morning and then at noon. The dosage usually starts at 200 mg and is gradually increased to 400 mg until the physician is satisfied that the patient is reaping the full benefits of the medication. For obstructive sleep apnoea, the standard dosage is 200 mg a day, taken in the morning. Shift work sleep disorder sufferers are instructed to take their 200 mg an hour before they start their work shift.
Using Modafinil as a brain enhancer
When Modafinil is taken to enhance cognitive ability, it is recommended that you start with 100 mg in the morning, and then a further 100 mg, if necessary, at noon. Modafinil remains in the system for 15 hours, leaving you ready to sleep normally when your bedtime comes around.
However, different people react differently to the drug, depending on weight and body chemistry, and the tasks facing them on any given day. Whereas a woman of 140 pounds juggling the normal stresses of working and caring for her family might find 50 mg at noon and an additional 25 mg at 5 pm sufficient for her needs, a student staying up all night writing an essay or studying for an exam might need more than 200 mg, spread out over 24 hours.
Often 4 mg per kilogram of body weight is recommended as a daily dose. Studies indicate that anything more than 600 mg a day is not safe; a 1999 study found that dosages of 800 mg a day led to increased blood pressure and heart rate, and should be avoided. It is recommended to start with a low dose and work up until you achieve the desired results for you in alertness, increased cognitive function, and wakefulness.