In this chapter, the authors discuss some of the problems that children with autism spectrum disorders (ASDs) have with sleep and discuss some of the reasons why these problems exist. For younger children, sleep problems center around resistance to going to bed, anxiety, and night awakenings, while adolescents have more problem with difficulties falling asleep, staying asleep, and being sleepy during the day. For many children with ASDs, the development of more typical sleep patterns can take much longer. Keeping a sleep diary for at least a week to give a detailed accounting of the times, routines and problems parents are encountering can be very helpful. Like head banging and body rocking, grinding of the teeth bruxism is fairly common in typically developing children. Keep in mind that some medical problems, as well as some medicines and foods or drinks that have caffeine, give people problems with sleep.