Thanks for your responses guys. Im still working and as i work with severely autistic children i really need to be alert at all times - im often tired anyway and this job does wear me down so the last thing i need is a drug so make me even more tired!

I should probably wait until the next set of school holiday and then try it to see how it affects me.

Or i may wait until i can see my pain cons again and ask him if there is anything else similar i can use that has a lesser chance of making me tired and drowsy....