Teenagers need about 8 to 10 hours of sleep every night to be at their best, but many fall short of getting that amount consistently. Lack of sleep can affect attention, mood and daily functioning in any teen. But the consequences may be magnified in teens with attention-deficit/hyperactivity disorder (ADHD). Unfortunately, sleep problems are very common in this group. Prevalence estimates vary, but studies suggest that 30% to 75% of youth with ADHD don’t get enough sleep.