It sounds like the 20 mg dose is too high for you and makes you sleep. Rather than increasing your dosage, you should try asking your doctor to decrease it back to 10 mg again, since that worked well for you. Not all people with ADHD need to be on a higher dose. Since methylphenidate has been helping you at 10 mg, you may not need to try a different stimulant. Try to get back in to see your doctor soon and tell her/him the same things you wrote here. Since you are taking Methyphenidate SR (sustained release,) you shouldn’t try cutting the pill or capsule in half since you’ll get too much medication all at once.