Sleep Aids.Ashwagandha dosage usually ranges from 450 to 2,000 milligrams per day, according to Drugs.com. Brew the herb as a tea by boiling between 3/4 and 1-1/4 teaspoon of ashwagandha root in 8 ounces of water for 15 minutes, instructs the Blue Shield website; you may drink three cups a day....