? Hypernycthemeral Syndrome – Definition and Explanations


the hypernycthemeral syndrome, also called free-running syndrome, is a sleep disorder that is part of circadian rhythm disorders. This is associated with the lack of synchronization of the normal endogenous circadian rhythm (about 25 hours) with the donors. time (Time, by man…called synchronizers (light, physical activity (Physical activity includes both daily life, at home, and physical exercise.), social). In normal subjects, thanks to these time donors, the physiological 25-hour rhythm is constantly resynchronized within 24 hours. In subjects, the sleep-wake rhythm (as well as some other circadian rhythms) is 1-2 hours longer.


Syndrome (A syndrome is a collection of clinical signs and symptoms to which a patient is susceptible…) it is rare, the frequency of which is not well described.


There may be several factors in the development and maintenance of this syndrome:

The blindness (Blindness is the condition of a person who is deprived of sight. The term blindness…)

Blindness leads to the loss of this important synchronizer of the circadian rhythm. But not all blind people have it hypernycthemeral syndrome (Hypernyctemeral syndrome, also called free course syndrome…). 50-85% of blind people retain sensitive anatomical structures light (Light is a collection of visible electromagnetic waves…) they are not prone to whole and free running syndrome.

personality disorders

In subjects with a certain pathological personality profile (Schizoid Personality Disorder), which sometimes results in very significant social isolation, the absence of a social synchronizer can lead to hypernycthemeral syndrome.

Lesion origin

Traumatic or tumor lesions of the suprachiasmatic region (localization of the internal clock).

Genetic factors

a polymorphism he was ashamed (A gene is a sequence of deoxyribonucleic acid (DNA) and…) coding melatonin (Melatonin, often referred to as the sleep hormone, is best known as…) seems to be at the beginning of the tendency to this syndrome. Finally, in certain subjects the unusually long endogenous period (more than 25 hours) makes synchronization with the donors’ time impossible.


Clinical aspects

There is a chronic daily shift during the period to sleep (Sleep is a natural recurrent loss of consciousness (but without losing…) 1 hour to 2 hours. Depending on the period in which the subject is faced, he may show manifestations related to the syndrome of advance. phase (The word phase can have several meanings, it is used in several fields and…) sleep, delayed sleep phase syndrome, or the absence of manifestations, if then the rhythm coincides with the normal social rhythm. The sleep-wake rhythm falls to 25 hours or more.

Additional tests

In addition to assessments in delayed sleep phase syndrome (Sleep Agenda, acting (Measure and record using an actimeter.), dose (In analytical chemistry, dosing is the act of determining a quantity…) salivary melatonin, polysomnography), a psychiatric evaluation, as well as a complete neurological evaluation with imaging studies if a suprachiasmatic lesion is suspected, seems necessary.


The results of therapy are generally very disappointing.

Donors who allow for resynchronization may be offered tighter timing. The light therapy (Light therapy is primarily a psychiatric treatment… can also be offered (2 hour morning schedule with 30 advance minute (The original form of the document: Law: minute one…is the original) per day) Melatonin can also be tested as well vitamin B12 (Vitamin B12 (or cobalamin) is a water-soluble vitamin that ensures good production…).

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