Psicofisiologia

NEURONAL RECOVERY TO THE REORGANISATION OF

NEURONAL CIRCUITS: A REVIEW OF THE FUNCTIONS OF SLEEP

Summary. Aim. To analyse the data and concepts that have been produced in relation to one of the functions that have been

suggested for sleep, namely, neuronal recovery. Development. Sleep is a state of consciousness that is different to that of

arousal. Mammals devote an important part of their lives to sleeping; for example, as humans, we sleep for a third of our lives,

but why do we spend so much time in a state where we lose contact with our surroundings? What would happen if we didn’t

sleep? Total sleep deprivation alters cognitive processes such as memory or attention, and if this deprivation is prolonged, the

individual deteriorates and dies. It has been suggested that sleep provides the organism with time to recover from the wear and

tear that occurs during the waking state and, given that the first effects of the absence of sleep are seen to affect processes that

are directly dependent on the brain, it has been claimed that its main purpose is to allow neuronal recovery. In this work we

analyse some of the studies on the effects of total sleep deprivation in humans and rats, as well as the relationship between

sleep and the neurotrophin system, which promotes neuronal survival and recovery. Finally, the latest theories about the

function of sleep are discussed. Conclusions. Neuron recovery is not the ultimate purpose of sleep; rather it is to allow for

maintenance and reorganisation of neuronal circuits, including new synapse formation, which enables existing neuronal

networks to be modified by the effect of experience, and all this makes it possible for the brain to work properly and to adapt

itself to the environment. [REV NEUROL 2006; 43: 409-15]

Key words. Functions of sleep. Neuronal recovery. Neuronal survival. Neurotrophins. Sleep deprivation.

Aceptado tras revisión externa: 24.05.06.

a Grupo de Neurociencias. Departamento de Fisiología. Facultad de Medicina.

b Departamento de Neurociencias. Instituto de Fisiología Celular. Universidad

Nacional Autónoma de México. México DF, México.

Correspondencia: Dr. Óscar Prospero García. Departamento de Fisiología.

Facultad de Medicina. Universidad Nacional Autónoma de México. Apdo.

Postal 70-250. México DF, 04510, México. Fax: (+52 55) 5622 5607. E-mail:

opg@servidor.unam.mx

Este trabajo contó con la beca DGAPA-UNAM IN230503, otorgada a OPG.

Agradecimientos. A los psicólogos K. Guzmán, por la realización de la figura

1, y E. Soria-Gómez, por la revisión critica de este manuscrito.

© 2006, REVISTA DE NEUROLOGÍA

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