Sleep/wake cycle

The synchronised oscillatory activity between the intrinsically linked thalamus and cortex. Under normal circumstances there is a level of activity which changes during the sleep-wake cycle increasing during periods of slow wave sleep. Excess synchrony occurs in conditions such as epilepsy. Thiazolidinedione... 

From time to time it has been suggested that histamine has some role in a number of behaviours and motor activity while the established and marked sedative effect of Hi receptor antagonists, mentioned at the start of this section, has consistently been considered to indicate a role for histamine in arousal and the sleep-waking cycle (see Chapter 22). 

These rhythms seem to be innately programmed although they can be adjusted. For instance, in a normal environment, the sleep-waking cycle of humans is obviously synchronised ( entrained ) with the (24-h) dark-light cycle whereas it assumes a period of around 25-27 h in a (time-free) environment where there are no diurnal cues. Interestingly, when humans are in a time-free environment, the change in the rhythm of... 

Figure 22.1 Pathways projecting to and from the suprachiasmatic nucleus (SCN). Inputs from photoreceptors in the retina help to reset the circadian clock in response to changes in the light cycle. Other inputs derive from the lateral geniculate complex and the serotonergic, Raphe nuclei and help to reset the SCN in response to non-photic stimuli. Neurons in the SCN project to the hypothalamus, which has a key role in the regulation of the reproductive cycle, mood and the sleep-waking cycle. These neurons also project to the pineal gland which shows rhythmic changes in the rate of synthesis and release of the hormone, melatonin...

Probably the most important breakthrough in sleep research came in the mid-1930s when it was discovered that the profile of the electroencephalogram (EEG) changed markedly during the sleep-waking cycle (Fig. 22.4). To this day, the EEG is a major... 

Table 22.1 Effects of activation of 5-HT receptors on sleep-waking cycle...

Since most excitatory transmission is mediated by glutamate this must be involved in the sleep-waking cycle. It certainly mediates the input of the retinohypothalamic tract to the SCN, apart from afferent inputs more generally to the ARAS, etc. So far, specific in vivo manipulation of the direct glutamate input to the SCN has not been possible. 

Garcia-Garcia, F and Drucker-Colin, R (1999) Endogenous and exogenous factors on sleep-wake cycle regulation. Prog. Neurobiol. 58 297-314. 

Portas, CM, Bjorvatn, B and Ursin, R (2000) Serotonin and the sleep-wake cycle special emphasis on microdialysis studies. Prog. Neurobiol. 60 13-35. 

Promote appropriate patient sleep-wake cycles... 

If patient is sleep deprived, consider altering the patient s environment and possibly a nighttime sedative to promote an appropriate sleep-wake cycle... 

Studies of sleep-active neuronal discharge across the sleep-wake cycle in freely moving animals provide important information about the hypnogenic process (see below) but, because of sampling limitations, are not suitable for systematic mapping of the exact locations of putative hypnogenic neurons. The application of the c-Fos immunoreactivity (IR) method to map sleep-active neurons has stimulated several advances. C-Fos IR is a marker of neuronal activation in most brain sites immunohistochemically labeled neurons can be mapped systematically. The localization of c-Fos IR following sustained sleep, but not... 

Nitz, D. Siegel, J. M. (1996). GABA release in posterior hypothalamus across sleep-wake cycle. Am. J. Physiol. 271, R1707-12. 

A number of clinical and preclinical observations published prior to the era of modern neuroscience gave clues as to the brain areas that are involved in the control of the sleep-wake cycle (Fig. 2.1). The Viennese neurologist Constantin von Economo observed patients suffering from extreme insomnia... 

El Mansari, M., Sakai, K. 8r Jouvet, M. (1989). Unitary characteristics of presumptive cholinergic tegmental neurons during the sleep-waking cycle in freely moving cats. Exp. Brain. Res. 76, 519-29. 

Lee, M. G., Hassani, O. K. 8r Jones, B. E. (2005). Discharge of identified orexin/ hypocretin neurons across the sleep-waking cycle. J. Neurosci. 25, 6716-20. 

Lee, R. S., Steffensen, S. C. Henriksen, S. J. (2001). Discharge profiles of ventral tegmental area GABA neurons during movement, anesthesia, and the sleep-wake cycle. J. Neurosci. 21, 1757-66. 

Aston-Jones, G. Bloom, F. E. (1981). Activity of norepinephrine-containing locus coeruleus neurons in behaving rats anticipates fluctuations in the sleep-waking cycle. J. Neurosci. 1, 876-86. 

Cespuglio, R., Gomez, M. E., Faradji, H. Jouvet, M. (1982). Alterations in the sleep-waking cycle induced by cooling of the locus coeruleus area. Electroencephalogr. Clin. Neurophysiol. 54, 570-8. 

GABA(B) receptor antagonist on the sleep-waking cycle in the rat. Brain Res. 773, 8-14. 

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