Sleep problems are one of the most common complaints in both the general health and mental health settings. It has been estimated that over 20% of the adult population suffers from some form of lasting insomnia at some time in their lives. Sleep disturbances may occur as a result of other co-existing physical or mental disorders or may occur independently of other disorders.

The majority of people will experience at some stage in their lives a period of transient or short term insomnia (e.g. 3 weeks or less) that is not classified as a disorder. Insomnia is characteristic by both lack of sleep and excessive worry about sleep disturbance. Insomnia is not defined by the amount of sleep per se. That is, the individual perceives that their sleep is insufficient and/or abnormal, such that it is significantly impacting on their daily functioning.

 (Ref: Management of Mental Disorders, World Health Organisation Collaborating Centre)