2 weeks аgо а 10-yeаr-оld bоy started Vyvanse (lisdexamfetamine) for ADHD. He takes the medication every morning at 7AM before leaving for school. His attention and hyperactive and impulsive behaviors have improved greatly since starting the medication, but he has been tired. His parents report he hasn’t been able to fall asleep since starting Vyvanse. Which of the following is an appropriate recommendation?