Most (but not all) ADHD medications are stimulants – that is, they stimulate the nervous system to help people focus. However, they can also make it difficult to fall asleep, much like drinking caffeine later in the day. In order to reduce the effect of your ADHD medications on sleep, you can work on the rest of your sleep habits: avoid caffeine, get at least 60 minutes of physical exercise daily, go to bed and wake up at about the same time every day (even on weekends), and turn off all lights and electronics (such as TVs and cell phones) in your bedroom.