The Butterfly Effect, by Eric Bress

Evan Treborn grows up in a small town with his single working mom and his friends. He suffers from memory blackouts where he suddenly finds himself somewhere else, confused. Evans' friends and mom hardly believe him, thinking he makes it up just to get out of trouble; something bad always seems to happen during these blackouts. As Evan grows up he has less of these blackouts until he seems to have recovered. Since the age of seven he has written a diary of his blackout moments so he can remember what happens. One day at college he starts to read one of his old diaries, and suddenly a flashback hits him like a brick!