My adderall (amphetamine salts) is my all-time favorite CFS medication of many that I have tried (Valcyte made me sicker, and not just because of Herxing). Cut right through the brain fog, but even though my doctor knows to my medication dosages low because of CFS, I still had to cut it down twice more. Loved the brain power of 10 mg, but couldn't sleep and I would get TOO focused - get involved in something and not realize that 6 hours had gone by before I look up from the computer. 5 mg - a subclinical dose - has improved my brain fog considerably and not affected my sleep. As a general rule, I have found that it's a good idea if BEFORE YOU GIVE UP ON A DRUG, TRY TAKING IT AT A MUCH LOWER DOSAGE.