Can i take half of ambien (zolpidem) before o go to bed then the other have in the middle of the night when i wake up?

Yes: But try to take it only when you have at least 4 more hours, or you might be sedated when you wake, and in rare cases, act without any memory for what you do. The cr tab should not be broken, but the immediate release tab can be divided. That's better than taking two, as it helps keep you from getting too used to them-- which would eventually reduce their effectiveness.

Not a great idea: You can do that, but you will probably find yourself very groggy in the morning. It sounds like your sleep is not good. I would work on your " sleep hygiene" -- no caffeine after 1 pm, get exercise but not within 2 hours of bed, only use your bed for sleep or sex, have the same bedtime and wake time every day ( even weekends). It's also worth talking to your doctor about other issues for you.