There is usually no single cause of insomnia but, in addition to medical causes, there are a number of factors known to contribute, including certain personality traits, lifestyle habits and life situations. The most common form is acute insomnia triggered by a change in the patient's life situation. If the patient reacts to insomnia by worry, it may lead to a state of hyperalertness which in turn will perpetuate (chronic) insomnia (functional insomnia). A careful history is crucial in evaluation, and a sleep diary is a useful additional tool. A good doctor-patient relationship and a non-pharmacological approach are the primary elements oftreatment.