Sleep mechanisms

Jouvet, M (1974) The role of monaminergic neurons in the regulation and function of sleep. In Basic Sleep Mechanisms (Eds Petre Quadens, O and Schlag, JD), Academic Press, New York, pp. 207-236. 

Jouvet, M. (1984a). Indolamines and sleep-inducing factors. In Sleep Mechanisms, ed. A. Borbely J.-L. Valatx, pp. 81-94. Berlin Springer-Verlag. 

Koella has reviewed the evidence implicating the involvement of serotonin in the sleep-wake cycle but the involvement of specific serotonin receptor subtypes in sleep mechanisms is unclear. Experimental evidence suggests that 5-HTia agonists delay the onset of REM sleep while 5-HT2 antagonists suppress REM and have variable effects on non-REM sleep. 

A Concluding Note on Sleep Deprivation and Sleep Mechanisms. . 567... 

The compensations for lost sleep suggest that the master control of total sleep may not reside in specific, localizable sleep effectors or neuromodulators, but in a stimulus generated by the need for sleep. Presumably, this need-stimulus activates several sleep centers and substances and deactivates wake centers and substances, which then contribute to the production of sleep to the extent that they are affected. (Conceivably, a need for wakefulness might conversely activate wake mechanisms and deactivate sleep mechanisms.) If one sleep or wake effector were destroyed or blocked by experimental or natural intervention, the need-generated stimulus would opportunistically recruit whatever systems were available to answer the need. When the need was satisfied, the effector systems would remain inactive no matter how prepared they were to function. 

Although this perspective parsimoniously encompasses the multiplicity of wake-sleep mechanisms, their plasticity and redundancy, the relative stability of total sleep, and rebounds following sleep deprivation, it suffers from a lack of critical, direct evidence. We have no better idea of what the major need-generated stimulus might be than we have of whether there is a master control mechanism. Only further, successful research can resolve these issues. 

Horner RL (2000) Impact of brainstem sleep mechanisms on pharyngeal motor control. Respir Physiol 119 113-121... 

K. Akert, C. Bally and J, P. Schade, Eds., "Sleep Mechanisms", Progress in Brain Research, Vol. 18, Elsevier Publ. Co., New York,... 

The whole field of research can reasonably be described as being revolutionized over a few years at the turn of the century through the discovery of two neuropeptide transmitters produced by cells of the hypothalamus. These hypocretins (Hcrt-1 and Hcrt-2), which are also known as orexins, are clearly the key to understanding narcolepsy, and a good deal of the normal sleep mechanism. The familial canine narcolepsy cases are associated with genetic mutations of this system, mice with targeted deletions of the gene for the precursor of these peptides display symptoms of narcolepsy, and the majority of humans with narcolepsy and the associated HLA characteristics have no detectable hypocretins in their cerebrospinal fluid. 

Neurotransmitters are compounds which are stirred in nerve terminals and which are secreted by these neurons to relate information from one neuron to another neuron. The structures of several well identified neurotransmitters are given in Figure 2. As recognized by Ralph Adams in the early 1970 s, dopamine, serotonin, norepinephrine, and epinephrine are of particular interest from an electrochemical point of view because they are easily oxidized and, thus, can be detected by the amperometric and voltammetric techniques[20]. It also turns out that these chemicals are of particular importance in normal neuronal function. For example, serotonin is thought to be important in the regulation of sleep mechanisms. Dopamine is thought to be important in the regulation of motor function as well as the control of mood and emotion[21]. Therefore, it would be desirable to measure the concentration of these species in extracellular fluid and relate this to neuronal activity. 

Molecnlar Mechanisms Underlying Sleep Focns on GABA... 

Much has been discovered recently regarding the molecular mechanisms and pathways involved in sleep and its associated disorders. It is hoped that this knowledge will lead to improved therapeutics lacking the side effects of currently available drugs. 

Caffeine binds to adenosine receptors in the brain, preventing adenosine from inducing sleep or opening blood vessels. Caffeine also increases levels of dopamine, the neurotransmitter associated with pleasure. This is the chemical mechanism for addiction. The response to adenosine competition causes increased adrenaline flow. 

In humans, poor sleep correlates with low plasma melatonin and can be improved by melatonin administration. This therapeutic approach has been tried especially in individuals whose sleep rhythms are disrupted by shift-work, blindness or jet-lag but its benefits are as yet unconfirmed and, in any case, the mechanisms by which it might reset sleep patterns are unclear. Of course, it must be remembered that other body... 

Hobson, JA (1992) Sleep and dreaming induction and mediation of REM sleep by cholinergic mechanism. Curr. Opin. Neurobiol. 2 759-763. 

Steriade, M (1992) Basic mechanisms of sleep generation. Neurol. 42 9-18. 

If the change in cortical electrical characteristics is permanent, why don t seizures occur all the time This is probably because the occurrence of an individual seizure depends upon an interplay of environmental and internal brain factors which from time to time result in loss of the normal mechanisms that contain and control abnormal neuronal firing. Some common factors are sleep loss and fatigue, but it is impossible to determine what sets off a particular seizure in most patients. 

Describe the mechanisms of the sleep disorders covered in this chapter, including insomnia, narcolepsy, restless-legs syndrome, obstructive sleep apnea, and parasomnias. 

Did we but know the mechanical affections of the particles of rhubarb, hemlock, opium and a man, as a watchmaker does those of a watch,. .. we should be able to tell beforehand that rhubarb will purge, hemlock kill and opium make a man sleep. 

Hydroxy tryptamine, or serotonin, is a neurotransmitter in the central nervous system (CNS). The nerve-cell bodies of the major serotoninergic neurones are in the midline raphe nuclei of the rostral pons, and ascending fibers innervate the basal ganglia, hypothalamus, thalamus, hippocampus, limbic forebrain, and areas of the cerebral cortex. The serotoninergic system plays an important role in the control of mood and behavior, motor activity, hunger, thermoregulation, sleep, certain hallucinatory states, and some neuro-endocrine mechanisms. 

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