My son is 8 years old an he wakes up in the middle of the night or very early i feel like he is not getting enough rest. why can't he sleep?

Not sure: Does he complain of nightmares? What does he eat before bed? Some foods can cause night waking. Have you had him see a chiropractor? Sometimes an adjustment helps sleep. Does he sleep with the tv on? Does he have led sources in his room that can cause disturbances? This may be worthwhile discussing with your pediatrician. And he may be getting plenty of sleep for him....