In addition, sleep disorders often occur secondary to
developmental disabilities. For example, sleep problems
affect about 30 percent of children who have cerebral palsy,
epilepsy, brain injuries and spina bifida. Between 25 and 50
percent of children who have attention deficit hyperactivity
disorder also have sleep disorders. Brain tumors and their
treatment also can cause brain injuries and subsequent
hypersomnia.
More often, primary-care providers will see hypersomnia
resulting from secondary causes, such as brain injuries
(see next section) and disorders that fragment nighttime
sleep. Disorders that fragment sleep include restless leg
syndrome, sleep apnea, nocturnal seizures, and periodic limb
movement disorder.