Spasticity is usually caused by central nervous system injuries, such as brain injuries or spinal cord injuries. Spasticity is a little different from stiffness.
One of the things that was identified through research is that patients with cerebral palsy have higher rates of depression and anxiety than you would see in the general population.
Sleep is important to all of us, but it's especially important for infants. When infants go to sleep, they start to create neural networks about what they've been learning during the day. It's estimated that as many as one in five children with disabilities have a sleep disorder, and that's higher than the rate of typically-developing children. Finding sleep interventions for these children is incredibly important so they can lay down their brain networks and continue to learn during their early childhood years.