Delayed sleep-phase syndrome (DSPS) is more common than ASPS and it affects about 0.15% of adults. It usually starts in early childhood or at puberty. Some cases that start at puberty go away when the person is about 20 or 21 years old. DSPS is much more common in teenagers than in adults. DSPS in people older than about 20 usually will have it all their lives, that is, it is chronic.