Sleep disturbances after traumatic brain injury are very common and may interfere with recovery and adversely affect cognitive function. The prevalence of sleep disorders ranges from 30% to 70%, depending on the time since trauma and diagnostic criteria. The incidence of sleep disorders is highest in the acute phase, but patients with chronic sleep problems are also numerous. The initial trauma may result in damage to neuronal structures that are important in regulating sleep, such as the reticular activating system. In the acute phase, environment, medications, pain, stress, cognitive deficits, and behavioral problems may all contribute to sleep disorders, but maladaptive behaviors and thoughts may develop and contribute to the persistence of these sleep problems. Specific sleep disorders such as obstructive sleep apnea and restless legs syndrome may predate traumatic brain injury and may require treatment whether known or not. Non-pharmacological treatments for insomnia primarily include environmental changes, relaxation techniques, and behavioral therapy. Many medications can also be used to treat insomnia, such as: benzodiazepines, antidepressants (especially tricyclic antidepressants), and non-benzodiazepine tranquilizers. All of these medications have potential cognitive side effects and the pros and cons must be carefully weighed before using them in patients recovering from brain injury. Whenever a sleep disorder is identified or treatment is initiated, it is important to objectively assess the efficacy of the treatment used, as patient self-reports may be inaccurate.