WBTB means "wake back to bed", it's where you wake up for a while, do quiet activities (think about LDig, meditate) and then go back to sleep. When you go to sleep after waking up a little bit you have more awareness. LD research showed that this can boost the %age likelyhood of lucidity by quite a lot (and many DV members agree that this helps quite a bit). Generally around the 5th hour after bed is the recommended time since after that your REM cycles start to get longer and closer together. There's a lot of introductory material here on DV, you should definitely check it out since it covers all the basics like WBTB. How long you stay up depends on how quickly you wake up. A lot with lucid dreaming is experimenting and finding out the ideal timing of things like WBTB (when to get up? For how long?)

A couple times now after galantamine and choline I have a bit of a headache during the next day. I felt fairly dizzy a lot of the day after taking just 5-HTP the other night at bedtime.