PHARMACOLOGICAL TREATMENT OF CHRONIC INSOMNIA

Insomnia is defined as the inability to get the amount or quality of s leep necessary for optimal functioning and well being. Long term or ch ronic insomnia has been conventionally considered to be that lasting f or at least 21 to 30 nights; however, it usually persists for months o r years. It is more frequent in women than in men, and becomes more pr onounced with age. Chronic insomnia is associated with mental disorder s, psychophysiological conditions, inadequate sleep hygiene, neurologi cal disorders and drug dependency. The most prevalent diagnosis is chr onic insomnia associated with psychiatric disorders, followed in prece dence by psychophysiological conditions. In chronic psychophysiologica l insomnia, idiopathic insomnia and insomnia associated with generalis ed anxiety, nonpharmacological strategies and sleep-promoting medicati on (e.g. hypnotics) are indicated. In patients with chronic insomnia a ssociated with major depressive disorders, antidepressants that induce acute sedation (e.g. amitriptyline, doxepin, trazodone) represent the primary drug treatments of choice. When necessary, hypnotics can be a dded. Currently used hypnotics include benzodiazepine derivatives, the cyclopyrrolone zopiclone and the imidazopyridine zolpidem. Hypnotics with a short half-life show the best profile of efficacy versus advers e effects with regard to morning awakening and daytime functioning. In patients with chronic insomnia, hypnotics reduce sleep-onset latency, decrease the number of nocturnal awakenings and reduce the time spent awake. The increase in total sleep time is related to greater amounts of non-rapid eye movement (NREM) sleep. Few differences exist between benzodiazepines, zopiclone and zolpidem in terms of effectiveness in inducing and maintaining sleep. However, in contrast to the benzodiaze pines and zopiclone, zolpidem does not suppress slow-wave sleep. Sleep laboratory and clinical studies tend to indicate that benzodiazepines are only effective when administered for relatively short periods of time in patients with chronic insomnia. Furthermore, a rebound insomni a has been described for short- and intermediate-acting benzodiazepine s and zopiclone, and a withdrawal syndrome, denoting the presence of p sychological and physical dependence, follows the abrupt cessation of benzodiazepine administration. In contrast, no evidence of tolerance o r rebound insomnia has been observed in relation to zolpidem administr ation.