The evaluation and treatment of sleep disorders represent an important area of research and clinical practice. Attempts to improve disturbed sleep are often needed, and treatment of the primary disorder associated with the insomnia, rather than the symptom of sleep disturbance, is always desirable. Our insight into sleep physiology and homeostasis is, however, rather limited. There may be several causative factors behind sleeping problems, and the treatment must be chosen accordingly. Of the drugs marketed, benzodiazepines are the drugs of choice, but other types of drugs are often useful in selected patients. The pharmacological profiles of the various types of benzodiazepines differ markedly from one another. The rate of distribution of the drug determines the duration of effects after a single dose whereas the elimination half-life is the determining factor during continuous intake. A treatment programme based on the individual patient and the type of sleep disturbance is usually necessary. An understanding of the quality and occurrence of such phenomena as carry-over, withdrawal and rebound effects as well as dependence problems reduces treatment complications and unnecessary use of sleeping pills. A good patient/doctor relationship is also needed to minimize the potential risks as well as the unnecessary use of hypnotic drugs.