This paper is on insomnia. Primary insomnia is defined by the Diagnostic and Statistical Manual of Mental Disorders as the difficulty of initiating or maintaining sleep or sleep of the non-restorative type for at least a month.(Espie 2002) Insomnia is transient when it lasts only for a few days to a few weeks, as when some temporary event or physical condition is responsible, such as an illness, changes in sleeping environment, work or family stress or jet lag. The cause or causes will pass or can be disposed of directly but when the disorder occurs between a month and six months, it is called acute insomnia, and beyond six months, it is chronic. This type is distinguished from the "psychophysiologic insomnia in wakefulness, the circadian rhythm disorder in time alignment, the parasomnias and secondary insomnias.
