Almost everyone thinks teen-agers don’t get enough sleep. What to do about it is something else.

Sleep specialists have been studying the problem for more than two decades. The American Sleep Disorders Association says that the average teen-ager needs about 9.5 hours of sleep per night, possibly because hormones that determine growth and sexual maturation are released mostly during slumber. Yet the association has found that teen-agers get an average of only 7.4 hours of sleep a night – more than two hours short of what they need.

Results of this sleep shortage include drowsiness in class, poor academic performance, moodiness, sleepiness behind the wheel, poor health, and increased accidents of all sorts.

Typically, an adolescent high school student may get up at 6:30 a.m., catch a 7 o’clock bus for a class that starts at 7:30 or 8 a.m. Sports or other activities may come after school, then homework. What’s more, television and time on the computer can keep a teenager up even later, to say nothing about long sessions of “hanging out” with friends. Bedtime often is pushed back to midnight or beyond.

An easy answer is get them to bed earlier. But the specialists say teen-agers may operate on a different clock. Instead of “early to bed, early to rise,” their bodies may dictate late to bed, late to rise.

Still another angle is that studies show that adolescents in the throes of puberty need more sleep than young children. Yet schools customarily start teenage classes early and let younger children start later in the day.

Some high schools in Minnesota have been trying a novel solution. In the Minneapolis suburb of Edina, the high school day was shifted in 1997 from a 7:30 a.m. start to 8:30. The next year, seven Minneapolis high schools changed the starting time from 7:15 to 8:40 a.m. Most teachers found the students more alert in the first two school periods than they had been with an earlier start time. In Edina, a relatively prosperous community, teachers reported marked improvement in student behavior and school nurses found a drop in physical complaints and stress. In the lower-income Minneapolis schools, however, both teachers and students reported a drop in extracurricular activities and difficulties for some students with their after-school jobs.

The researchers said their findings were preliminary and warned that any schedule changes require full consultation with parents, students, teachers and staff.

Teenagers should see that times are changing. Some school administrators, at least, are coming to regard the sleepy ones as needing help rather than scorning them as slug-abeds and goof-offs.