Occupation:truck driver. in order to stay awake often i hit my head hard with my hand and now i have diplopia(a week ago).do you think it's temporary?

Diplopia: Yes. Diplopia from trauma is usually temporary. The cranial nerves at the base of the skull can be stretched from a blow to the head. Vision may be more difficult as the diplopia resolves because the images get closer together. Stop hitting your head to stay awake and consider a sleep study to exclude sleep apnea. Wearing an eye patch on alternating eyes can help speed recovery.

No, see Eye MD: Hitting you head with your hand should not cause diplopia. There are many serious causes including stoke, MS, and tumor. Would recommend evaluation by ophthalmologist.