The association of sleep and pain: an update and a path forward

The functions of mammalian sleep remain unclear. Most theories suggest a role for non-rapid eye movement (NREM) sleep in energy conservation and in nervous system recuperation. Theories of REM sleep have suggested a role for this state in periodic brain activation during sleep, in localized recuperative processes and in emotional regulation. Across mammals, the amount and nature of sleep are correlated with age, body size and ecological variables, such as whether the animals live in a terrestrial or an aquatic environment, their diet and the safety of their sleeping site. Sleep may be an efficient time for the completion of a number of functions, but variations in sleep expression indicate that these functions may differ across species.

Clues to the functions of mammalian sleep

Restricted and disrupted sleep: Effects on autonomic function, neuroendocrine stress systems and stress responsivity

Organisms must adapt to the temporal characteristics of their surroundings to successfully survive and reproduce. Variation in the daily light cycle, for example, acts through endocrine and neurobiological mechanisms to control several downstream physiological and behavioral processes. Interruptions in normal circadian light cycles and the resulting disruption of normal melatonin rhythms cause widespread disruptive effects involving multiple body systems, the results of which can have serious medical consequences for individuals, as well as large-scale ecological implications for populations. With the invention of electrical lights about a century ago, the temporal organization of the environment has been drastically altered for many species, including humans. In addition to the incidental exposure to light at night through light pollution, humans also engage in increasing amounts of shift-work, resulting in repeated and often long-term circadian disruption. The increasing prevalence of exposure to light at night has significant social, ecological, behavioral, and health consequences that are only now becoming apparent. This review addresses the complicated web of potential behavioral and physiological consequences resulting from exposure to light at night, as well as the large-scale medical and ecological implications that may result.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1600-079X.2007.00473.x

The dark side of light at night: physiological, epidemiological, and ecological consequences

The clinical use of deep brain stimulation (DBS) is among the most important advances in the clinical neurosciences in the past two decades. As a surgical tool, DBS can directly measure pathological brain activity and can deliver adjustable stimulation for therapeutic effect in neurological and psychiatric disorders correlated with dysfunctional circuitry. The development of DBS has opened new opportunities to access and interrogate malfunctioning brain circuits and to test the therapeutic potential of regulating the output of these circuits in a broad range of disorders. Despite the success and rapid adoption of DBS, crucial questions remain, including which brain areas should be targeted and in which patients. This Review considers how DBS has facilitated advances in our understanding of how circuit malfunction can lead to brain disorders and outlines the key unmet challenges and future directions in the DBS field. Determining the next steps in DBS science will help to define the future role of this technology in the development of novel therapeutics for the most challenging disorders affecting the human brain. Over the past 20 years, deep brain stimulation (DBS) has transformed the treatment of movement disorders. Now, new therapeutic possibilities for DBS are emerging for other neurological and psychiatric disorders. This Review considers the clinical and scientific advances facilitated by DBS and the crucial questions, challenges and opportunities that face this technology.

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Deep brain stimulation: current challenges and future directions

Sleep deprivation induced by the modified multiple platform technique: quantification of sleep loss and recovery.

Vigilance status was continually monitored in socially stable groups of rats exposed to the modified multiple platform (MMP) technique for sleep deprivation. For comparison, sleep parameters were also monitored in socially isolated rats deprived of sleep by the single platform (SP) method. In all cases, sleep was continuously recorded during baseline, during 96 h of sleep deprivation and during 4 days of recovery. Both multiple- and single-platform techniques completely abolished paradoxical sleep (PS) during the deprivation period, but also resulted in significant decreases in slow wave sleep (SWS) (31% and 37%, respectively). Unexpectedly, animals on large platforms, which are normally intended as controls, also showed significant reductions in PS and SWS, and these effects were more pronounced in rats deprived in groups than in animals deprived in isolation. Another control preparation, rats placed on wire-mesh grids in the deprivation tank, also showed PS reduction (39%) but no loss of SWS during the 4 test days. Paradoxical sleep rebound was observed in the first 24 h in all groups, except for grid controls. Overall, no significant differences were found between single- and multiple-platform procedures during the 4 days of deprivation. However, sleep rebound was more pronounced in MMP-deprived rats than in SP-deprived rats. Sleep loss in both control groups may reflect residual effect of stress that remain in the platform technique. These findings indicate that the MMP technique is effective in inducing PS deprivation (PSD). However, the fact that SWS is also affected may have implications for conclusions on paradoxical sleep function based upon paradoxical sleep deprivation. D 2004 Elsevier B.V. All rights reserved. Theme: Neural basis of behavior Topic: Biological rhythms and sleep

Research report Sleep deprivation induced by the modified multiple platform technique: quantification of sleep loss and recovery

The methods used to induce paradoxical sleep (PS) deprivation are believed to be stressful. In the present study, two methods were compared in regard to their ability to activate the hypothalamic-pituitary-adrenal (HPA) axis. Animals were placed on multiple large (MLP) or small (MSP) platforms or on single large (SLP) or small (SSP) platforms and blood sampled at the end of a 4-day period of PS deprivation (experiment 1) or on Days 1 (short-term) and 4 (long-term) of PS deprivation (experiment 2). ACTH and corticosterone (CORT) levels were determined by RIA. The results of experiment 1 showed that all experimental animals presented increased ACTH response, compared to controls. CORT levels, however, were only elevated in MSP animals, suggesting increased adrenal sensitivity. Experiment 2 showed that ACTH levels of MSP animals were higher than MLP and SSP animals, and that animals placed on the multiple platform tanks showed the highest ACTH levels on Day 4 of manipulation. CORT levels were elevated in the animals kept over small platforms, and these levels where higher on Day 1 than basal and further elevated on Day 4 of PS deprivation. These results indicate that the multiple platform technique induces a distinct activation of the HPA axis, and that PS deprivation may act as an additional stressor.

https://onlinelibrary.wiley.com/doi/pdf/10.1046/j.1365-2869.1998.00122.x

Increased acth and corticosterone secretion induced by different methods of paradoxical sleep deprivation

Deep brain stimulation reverses anhedonic-like behavior in a chronic model of depression: role of serotonin and brain derived neurotrophic factor.

Rats were deprived of sleep for 96 h by the platform technique and total glutathione (GSHtau) levels were measured in seven different brain areas. Glutathione levels were found to be significantly reduced in the hypothalamus of sleep-deprived animals when compared with large platform (-18%) or home cage (-31%) controls. Deprived rats also had reduced GSHtau levels in thalamus compared with home cage controls only. Glutathione levels did not differ among the three groups in any of the other brain areas examined. These results indicate that specific brain areas may be differentially susceptible to oxidative stress after sleep deprivation. The apparent vulnerability of the hypothalamus to these effects may contribute to some of the functional effects of sleep deprivation.

Débora Cristina Hipólide

Papers

Sleep deprivation induced by the modified multiple platform technique: quantification of sleep loss and recovery.

Research report Sleep deprivation induced by the modified multiple platform technique: quantification of sleep loss and recovery

Increased acth and corticosterone secretion induced by different methods of paradoxical sleep deprivation

Deep brain stimulation reverses anhedonic-like behavior in a chronic model of depression: role of serotonin and brain derived neurotrophic factor.

Sleep deprivation induces brain region-specific decreases in glutathione levels