cluster headaches
"Taking the medicine 60mg (reducing by 5 mg per day over 1 week) worked until the dosage got down to 40 mg,  then the headaches came back and the medicine was not effective at all.

I am now on my second week of the same approach from my doctor and am writing this as at 04:00.  I woke up at 02:00 and have not been able to sleep since. But, only 'normal' headaches so far."