After hitting your head, how long should you stay awake?

I fell of my bike and skidded a few feet. My arm, shoulder, wrist and the right side of my face are bruised and have little scs on them. I hit my head on the gr and dirt. I had a hard time breathing right after I landed, and when I walk around now, its hard to breath. I have to take short breaths because it hurts. Is it ok for me to go to bed? I'm really tired, but I'm afraid that I wont wake up. This happened around 5:00 PM today.