Complex sentence: When he comes to, he discovers that 8 years have passed and the year is now 1986; while he has not aged at all, his parents are now middle-aged and Jeff is 16 years old.
Split into simpler sentences: When he comes to, he discovers that 8 years have passed and the year is now 1986. While he has not aged at all, his parents are now middle-aged and Jeff is 16 years old.