Hypersomnia

        Hypersomnia is an excess of sleep, which differs from the normal one in duration, depth and quickness of appearance. Hypersomnia should be distinguished from the comatose state of sleep by its reversible character. The two forms of sleep correspond to two kinds of hypersomnia, some corresponding to the slow sleep phase and other to the quickly sleep one.

       As a definition, hypersomnia is characterized by excessive sleepiness that occurs almost every day in a person who sleeps normal at night(8-12 hours duration). The person with the disorder just wants to sleep during the day, but there are situations when sleep is installed unwittingly.

Hypersomnia related diseases

       Symptomatic hypersomnia (idiopathic) appears in a series of organic brain diseases such as encephalitis, toxic or metabolic encephalopathies, tumors, strokes or traumatic injuries. Unlike coma, the sleep in symptomatic hypersomnia is not continuous.

Hypersomnia pathogenesis

       Pathogenesis of the symptomatic hypersomnia depends on the factor that causes it. Thus, during symptomatic hypersomnia related to the hepatic encephalopathy (porto-cava encephalopathy in cirrhosis, liver cancer, hepatitis, etc.), the occurrence of symptoms and state of sleepiness is attributed to toxic substances resulted from the alteration of the hepatic cells. Of those, less known is ammonia, which combined with the alpha cetoglutaric acid blocks the Krebs cycle, thereby disturbing the oxidative metabolism of nerve cells and delaying the synaptic driving by inhibiting the cholinesterase.

       Hypersomnia related to the respiratory encephalopathy (chronic respiratory failure, Pickwick syndrome, etc..) is based on a complex pathophysiological mechanism. The increasing resistance of chest and lungs, mediastinal and diaphragm excessive obesity lead to excursurile respiratory and alveolar hypoventilation, accompanied by hypercapnia.

       In turn, hypercapnia causes decreasing the tone of the neurons involved in the mechanism of wake structures and may finally lead to a permanent superficial drowsiness. Symptomatic hypersomnia also occur in some endocrine diseases, especially in adrenocortical failure in hypothyroidism, etc. Some psychiatric disorders are accompanied by the so-called "psychogenic hypersomnia" manifested by sleepwalking, anxiety, schizophrenia, hysteria, etc.

       Brain tumors can cause this disease by affecting directly the nervous structures involved in sleep generation mechanism but also by producing intracranial hypertension. Hypersomnia in cerebrovascular disease present the consequence of an abnormal irrigation of the regions involved (thalamus, subthalamus, and diencefal stem regions ).

       Functional hypersomnia include hypersomnia in which no evident organic cause could have generated the excess of sleep. After the two forms of sleep have been individualized, premises were in order to distinguish functional hypersomnia, corresponding to slow sleep, to the other one, corresponding to paradoxical sleep (narcolepsy). There are also simple "essential" forms of hypersomnia (diurnal or nocturnal) in which sleep, although it takes more time than normal,is not accompanied by other clinical manifestations or bioelectrical anomalies.

       Functional hypersomnia may take several hours, days, even weeks and may occur at intervals from one month to several years. Other forms of functional hypersomnia can be accompanied by breathing disorders, so-called sleep apnea.

Hypersomnia incidence

       Although not enough data is known about the incidence of disease and comorbidities (diseases associated) with mental disorders, many people with disorders related to excessive sleepiness in the sense of depression have symptoms that can enter criteria for a diagnosis of severe depressive disorders, as a psychosocial consequence of excessive sleepiness.

Hypersomnia facts

       Drowsiness may increase with age, which in fact is a normal phenomenon and also distinct from hypersomnia. But even if it is not very common Klein-Levin syndrome (the recurrent form of the disease ) affects 3 times more men than women, especially around the age of 15-30 years.