Hi, I Am A 46 Yo Female On Cymbalta 120mg/day.

Hi, I am a 46 yo female on Cymbalta 120mg/day. I'm wondering the best time of day to take it? At the moment (and the past few years) I take it at 7am. From approx 8am-3pm I am totally spaced out! Barely keep my eyes open, fall asleep at the computer, the lot. I also have chronic pain & am on MS Contin(slow release morphine sulphide in Australia) 60mg 3xday. This does not seem to bother me in the same way as I take a dose at 3pm with none of the above effects. Would it be ok to shift to taking Cymbalta before bedtime?
Thanks for your time!