Yes, this is unusual for a child his age. Generally, children should fall asleep within thirty minutes of going to bed and then sleep through the night. Is he falling asleep and then waking up, or is he having a problem falling asleep at all at the outset? Often during the summer children display either onset insomnia or middle insomnia and broken sleep becasue they get out of the habit of a regular sleep pattern. Circadian rhythms (involving body temperature, metabolism, heart rate, blood pressure) become upset and this results in sleep disturbance. It is important to go to bed and wake up at approximately the same time each day in order to establish and maintain a sound sleep pattern. This is important now that school is again approaching.
How long has this been going on? If this behaviour is recent, I wonder if your son just might be overly anxious about returning to school. Anxiety is often displayed in the behaviours you have indicated - sleep issues, fatigue, stomach aches.