showed that
adolescents require at least as much sleep as
they did as children, generally 8.5 to 9.25 hours
each night. Research also showed that many
adolescents undergo a sleep phase delay that
results in them both falling asleep and waking
up later. Thus the typical adolescent's natural
time to fall asleep may be 11 pm or later;
because of this change in their internal clocks,
teens may feel wide awake at bedtime