Sleep disorders, both insomnia and hypersomnia, are commonly associated wit
h various co-morbid conditions, including general medical and neurologic di
sorders, psychiatric illnesses, and secondary or symptomatic restless legs
syndrome/periodic limb movements in sleep. Diagnosis of the co-morbidity is
the first step in treatment, followed by an assessment of the sleep distur
bance. This begins with a complete history and physical examination, follow
ed by laboratory testing such as polysomnography, multiple sleep latency te
sting, and actigraphy. The treatment of sleep disorders caused by co-morbid
conditions is discussed under seven categories, including the use of gener
al measures (e.g., sleep hygiene, encouraging patients to develop good slee
p habits, medication), treatment of the co-morbid condition, treatment of i
nsomnia, treatment of excessive daytime somnolence, treatment of parasomnia
s, treatment of sleep-wake schedule disorders, and treatment of secondary o
r symptomatic restless legs syndrome.