Background Insomnia is one of the most common and frequently reported sleep complaints. It is expected that in any given year, about one third of the adult population may have some degree of insomnia or sleep difficulty (Lacks & Thorn, 1991). Insomnia is generally understood as a perception of deficient or poor subjective quality of sleep which leads to a feeling of being un-refreshed, either on waking time, during daytime or in both these situations...