I swear i can tell what nights I'm gonna get a cluster headache . Just before i fall asleep i start getting a aching feeling behind my left eye. On those nights it's a sure thing so last night when that happened i hit the 02 and it was still there so i took a 100mg oral imitrex and slept through the night.(5 hours) Kinda just wondering if anyone else has a warning? From what i read most say it comes on sudden and leaves the same way. I have had some without any warning but lately i feel like I'm recognizing the way my body sets up before the hit. I know imitrex isn't a preventative but i feel like it stops it before it builds. I save the injections for the full blown hits. also i usually don't get hit until 3a.m which would mean i'm getting a long warning.