Greetings! Motrin or ibuprofen, a NSAID works by blocking the body s production of certain natural substances that cause inflammation. This effect helps to decrease swelling, pain, or fever. The chances of this medication causing sleep disturbances are minimal to rare. So, the sleep disturbance the baby experiences now may be attributed to the fever or his illness, and they are very common with children. But if the baby develops easy bruising/bleeding, mental/mood changes, swelling of the ankles/feet/hands, unexplained weight gain, change in amount of urine, unusual tiredness or breathing difficulty while on motrin; consult a pediatrician right away.