By definition, insomnia entails a subjective component relating to the perception of poor sleep, which may and may not be supported by objective evaluation of sleep. Although polysomnography (PSG) is the objective method that provides a comprehensive measurement of sleep and is essential in diagnosing many sleep disorders, it is not usually necessary in the assessment of an insomnia complaint. Recent practice parameters for the evaluation of insomnia published by American Academy of Sleep Medicine states that PSG is not indicated for routine evaluation of chronic insomnia. PSG should be considered in the situations where the patient presents with pathologic levels of sleepiness, reported symptoms of other sleep pathologies (e.g., sleep-disordered breathing, periodic limb movements, parasomnias).